Ditto your remarks on the effects of temperature and humidity. I'd also add that the degree of sealing or isolation the cigars experience are also a factor. This latter point is primarily in reference to access to oxygen to support further oxidative changes such as aerobic reactions. These could not genuinely be regarded as fermentations though. The primary fermentation of cigar tobacco is the result of the biological action of a cluster of approximately four key bacteria.
Yep, I agree with you on the degree of sealing/isolation as well. I was attempting to keep my answer as simple as possible and focused only on the fermentation reactions that cause the ammonia. Of course, over time, this ammonia breaks down into various bi-products. This is primarily due to oxidation reactions. The NH3 (ammonia) when exposed to oxygen, initially breaks down to various nitrites. Additional oxygen will further oxidize the nitrogen to form various nitrates. I am making the assumption that these are the primary (not necessarily the only) reactions that remove the ammonia caused by fermentation.
Obviously, these reactions will increase in rate with greater amounts of oxygen. Therefore, if you open your box and let it sit in the open air, the ammonia will be gone much quicker than leaving it unopened for months on end in a humidor. Is this good or bad? MRN says it is bad. While you speed up the process, the end result is not as good as if you had allowed it to happen slowly. In the short term, I would argue that the cigars will be very similar, but in the long term they will not.
Why not in the long term? This is where the answer gets much more complicated and much less understood. Based on my reading, conversations, and knowledge of chemistry, I would surmise that the oxidation reactions are just a small part of the aging process. There are many more chemicals in the tobacco that break down over time. Just increasing the oxidation of the ammonia (and, obviously other chemicals) might allow for quicker smoking and shorter "sick" periods, but it will not allow the cigar to properly mature.
I could go into what some of these reactions are theorized to be, but I am already getting cramps in my fingers from typing.

Would love to continue this line of thinking, however. Holds great interest to me. :thumbs:
Finally, Wilkey, you stated that the fermentation is primarily caused by four strains of bacteria. Of course when you ferment grains, you end up with alcohol. I am assuming, therefore, that these fermentation reactions within the tobacco are anaerobic. Would explain the formation of ammonia. Is there correct?