Misah and Misah bidei shamayim

There is a fascinating machlokes on the last pasuk of parshas bamidbar - The Ramban and the Behag use the pasuk in the minyan hamitzvos as a lav for stealing from the klei shares.  The Rambam, however, thinks the pasuk is only a "remez" to stealing klei shares, but in the minyan hamitzvos, there is no such lav:

ואף על פי שאמרו (סנה' פא ב) רמז לגונב את הקסוה לא יבואו לראות, ויש די ספוק באמרם רמז ושפשטיה דקרא אינו כן. ואינו גם כן מכלל מחוייבי מיתה בידי שמים כמו שהתבאר בתוספתא (זבחים ספי"ב וכריתות פ"א ה"ב) ובסנהדרין (פג א

The Rambam defends his claim that there is no full-fledged lav for stealing klei shares by noting that there is no official punishment / misah bidei shamayim for this action.  Were one to be chayav misah bidei shamayim, then for sure it would be a full fledged lav - with no such chiyuv, its entirely possible / very plausible that while of course it is prohibited to steal klei shares, it is not a lav in its own right.

The Ramban jumps on this Rambam:  what do you mean that theres no chiyuv misah bidei shamayim?  The mishnah in sanhedrin lists 3 cases that kanain pogin bo - and stealing klei shares is one of them!  The mishnayos which list those issurim which have a chiyuv misah bidei shamayim leave out stealing klei shares not because it is less chammur - but rather because it is more chammur:  the list only includes those prohibitions whose sole punishment is misah bidei shamayim, not those, like stealing klei shares, which have an additional punishment of kanain pogin bo.

In the above formulation, the Ramban (based on gemara sanhedrin 82b) makes a global claim:  Chiyuv misah bidei adam, in all its forms (beis din, kanain pogin bo, kipah, etc.) includes within itself chiyuv misah bidei shamayim.  More strongly formulated: chiyuv misah bidei adam is predicated on and justified solely by the fact that this person is chayav misah bidei shamayim.  Otherwise, what right would we have to kill him?

The Megillas Esther points out that the rambam, based on another opinion in the gemara, seems to hold almost the entirely opposite position:  To the contrary, if one is chayav misah bidei shamayim, then it would be redundant to also have them be chayav bidei adam - let Hashem take care of giving his promised misah bidei shamayim.  The only role of misah bidei adam is in a case where a person is NOT chayav misah bidei shamayim - that is where it is sometimes constructive to have misah bidei adam.

This might just be a cute cheshbon, but this could explain an interesting lashon of the rambam in the peirush hamishnayos.  Another of the three cases of kanain pogin bo is a boel aramis - in that case, the gemara limits the right of the kanain to kill the boel aramis to the shaas maaseh aveirah - once the aveirah is over, the kanain cannot kill him anymore.  Some acharonim believe that this limitation only applies to boel aramis -- but by stealing klei shares, one can kill the ganav even after he has finished the maaseh gneivah.  Why the difference?

The Rambam says in peirush hamishnayos:
ו] קסוה, כלי שרת נגזר מן קשות הנסך. ומקלל בקוסם, הוא שיברך השם בשם עבודה זרה. ובועל ארמית, הוא שיבעול בת עובדי עבודה זרה בפרהסיא בעשרה ישראל או יותר, ובשעת מעשה דוקא כמעשה פינחס, אבל אחר שפירש, או שלא היה בקהל מישראל, או שלא היתה עובדת עבודה זרה, אסור להרגו. אבל הוא מחוייב כרת על בת עובד עבודה זרה ואף על פי שלא נזכר בתורה ולא נמנה מכלל הכרתות, אלא שהוא קבלה. ונתפרש במקרא במה שנאמר ובעל בת אל נכר יכרת ה' לאיש אשר יעשנה וכו'.

If I am correct, the rambam is saying the following:  By boel aramis, you cant kill him once the maaseh aveirah is finished because now he is chayav kares / misah bidei shamayim - and that we leave to Hashem to fulfill.  In the other cases, however, even after the maaseh aveirah, the person is not chayav misah bidei shamayim - therefore the kanain can still kill the avaryan. (the diyuk is better in the translations in the back of the gemara)

I think this machlokes Rambam / Ramban plays out lishitasam in a few other places:

In parshas lech lecha, the Ramban famously disagrees with the Rambam and says that if a navi prophesies that someone deserves to die, it is a mitzvah to kill them.  The Rambam, on the other hand, thinks that you're chayav misah if you kill someone due to such a nevuah.  The Ramban, lishitaso, thinks misah bidei adam is a function of misah bidei shamayim - if Hashem wants a person dead, as evidenced by nevuah, then that "chiyuv misah bidei shamayim" translates into a hetter of misah bidei adam.  But the Rambam thinks that misah bidei shamayim and misah bidei adam are two disjoint concepts - one does not lead to the other - so why should this prophecy translate into a misah bidei adam - if hashem wants to kill this guy, let Hashem kill him.

There is a famous din by eidim zomimin of kaasher zamam vilo kaasher asah.  That is, if witnesses perjure in an attempt to have someone executed by the courts and get found out before the guy is executed, then they themselves are killed.  After the fact, however, they're let off the hook.  The Ramban has a very fascinating explanation for why this should be:  Bikerev elokim yishpot - Hashem steers the hands of the sanhedrin - if the witnesses were found false before the execution of their victim, thats because Hashem is trying to save the innocent victim - therefore the 2 witnesses are guilty and liable to the death penalty.  If however, Hashem allowed the execution of the 'victim' to go through, it must be because the 'victim' wasn't really so innocent after all, and therefore the eidim did not kill an innocent man and are let off the hook.  This assumes the Ramban's shittah about the nature of chiyuv misah bidei adam- namely, that it is predicated on and built off misah bidei shamayim.  This does not even get off the ground, however, in the Rambam's opinion (and indeed, if I recall correctly, when the kesef mishnah tries to explain the rationale of kaasher zamam in the Rambam, he does not even mention shittas haramban.)

I don't know where exactly to go with this machlokes, but at least I'll end with the following observation. How does the Rambam answer the strong kashya of the Ramban: what could be the mechayev / justification to give misah bidei adam if not misah bidei shamayim?  I think the point is that when we seek justice here in this world, we don't attempt to play G-d - we can't know what G-d knows or take his global perspective in our justice system.  Misah bidei shamayim, we leave to shamayim.  What we can do is din bidei adam - and as long as we use the dinei hatorah to implement our dinei adam, then our din will also ultimately reach the level of being a true din tzedek.