I'm actually pretty interested in the gender aspect as well, but this does warrant some sort of closure...inasmuch as closure ever happens with philosophy.
Firstly, even if Megatron had wiped out the the human race, the planet would be far from lifeless. Plants and animals would still be around, which ties into... Paragraph 2, the variety of other factors I was thinking of mostly comes down to a species impact upon other species (as well as population numbers, lifespan, potential to procreate) - human beings have wiped out many, many species over the years, so to my mind their loss as a species would arguably allow many other species on Earth to 1: survive and 2: possibly flourish in a healthier ecosystem. Megatron was at most going to wipe out one species, and a species whose major power had imprisoned him (while he was helpless no less) and pillaged his body to make microwaves etc. Of course there is the don't judge all for the actions of a few etc, but then we get to Sideways and Demolishor in Shanghai. Similarly, though he didn't know or care, it was a species that was/is well to destroying itself anyway (interspecies war, pollution, etc.) - it could well be seen that he was merely hastening the inevitable, in such a way that would be unintentionally beneficial to the rest of the planet.
Thanks to humanity's poor choices, we're wiping out many species, quite possibly including our own down the track. At worst it's 2 species of equal moral merit (in terms of consequences for other species, different matter if you take it on the numbers - dunno how many TFs there were on Cybertron so it's difficult to judge), at best the Transformers have a greater 'right' to exist. What makes it especially interesting here is that it was the Autobots who jettisoned the Allspark to avoid losing a civil war, thus dooming their species (and bringing said war to Earth).
I guess the real lesson is, Movie Autobots make lousy houseguests - they won't share their toys and they inevitably bring gatecrashers.![]()