That much is clear. No one "owns" or "leads" EA, it's not a monolith; people have their own beliefs and co-opt it, including crazies. The only common tenet is in the name.
Notwithstanding that "shrimp welfare" and the like is in the margins, it does not preclude the overwhelmingly anthropocentric charitable giving by most members.
I mean, the most popular writer associated with that world, Scott Alexander, donated his kidney just to help others. Knowing the good people are trying to do, it's unseemly to me for EA not only to be discarded but viciously attacked because of "vibes" and weirdos who associate themselves with it.
You used the term "an excuse" twice; for what, a hidden motive to do harm? I think some types like Bentham's Bulldog are wrong or misguided in some respects, that doesn't mean you can leap to some notion that they want to harm humanity in the most stupid way possible: donating a meagre sum to shrimp welfare.