I think there’s a whole class of people, such as the author of the post in the screencap, for whom “activism” is a monolith, who just think of it all as some kind of do-gooding without considering the content at all.
This is not to bash on vegans; I think veganism is admirable and may eventually be morally necessary. But I can’t understand why someone would react to the well-documented gender & ethnic disparities in tech with “better make some vegan-friendly emojis for diversity”.