This isn't even politics per se, just feel good activism, the "I'm helping", while doing absolutely nothing that helps in the topic). Equivalent to thoughts and prayers.
"...dividing its pages between offering background on the real-life animals - and the reasons for their disappearance - and providing versions playable in D&D 5E and other RPGs."
Is learning why animals are no longer around controversial? This book seems like it does in fact teach facts and isn't doing absolutely nothing as you put it.
What part of any of this effort improves either the gameplay of backers or the state of conservation?
There is no need in any edition of the game for another book of 100 monsters. I already have hundreds of CR <1 small birds and mammals, and similar numbers of herd animals and apex predators. Even with "reimagined powers" it takes about 30 seconds to throw an extra power on a monster even in extra crunchy editions of the game.
My major question with any gaming product is what fun does this bring to my gaming table? And I don't see any fun that it'll add, at least not to my game. Most of what I see is some decent swag and some indulgences someone could buy for their feelings of guilt at conspicuous consumption in the hobby.
So... your issue is that someone... somewhere... has written a book... including a cause they believe in?
This doesn't even strike me as activism, unless you're uncomfortable with looking at a Dodo illustration in your D&D campaign. This is a book with extra monster ideas, some of which are inspired by animals you will never see. Even devoid of empathetic value towards those dead animals, you gotta admit it's pretty metal to fight an animal that doesn't exist... anymore.