It's not hard to see why a certain section of anime fans are pissed. They see anime as exactly the kind of media they want, free from """diversity""" or """politics""" or whatever other kind of weird bullshit they peddle to justify their hatred.Not watching the video since I don't want to give the guy a click, but I've seen people moaning about the original series in other places, and complaints always unironically include "sjw", "tumblr", etc. People just seem to insta-hate anything that's not made "for" them in terms of lacking incestuous/loli fanservice crap and being made mostly by an audience of women. Not sold on the art style or premise, but it might be decent and I can't say Crunchyroll is wasting their time by encouraging Western productions since there's a pretty big amount of people who are into anime who also watch anime-styled original English productions like Avatar, RWBY, or just cartoons in general.
It's also a medium that they're probably very protective of since it's so niche. To them, seeing one of the biggest western presences in anime promote a show that's at least making claims to be diverse is likely perceived as a literal attack. I can just imagine posts about how the 'sjw's' have invaded anime and are going to ruin it.