The "disgusting triggered woman" face in the lower left corner tells everything there is to know about the youtuber's politics. Consternating.
Cameron's last movies are an ode to whitewashing and his "strong" female characters are merely one level above the chainmail bikini warrior. OF COURSE most progressive-minded people won't appreciate him a lot.
(Which doesn't mean they hate him. Generally speaking, social justice circles are pretty much indifferent to the casual level of undeliberate misogyny random cishet men such as Cameron display. There's just bigger fish to fry, there's Weinstein and Polanski and Lars Von Trier etc.
And to say
Battle Angel Alita Gunnm has problems of sexualization is just stating the obvious.
Alita Gally is oversexualized and objectified. She's already presented that way in the manga for that matter.
The (shitty) movie downplays that aspect but doesn't remove it.
TL;DR: This youtuber is just another reactionary fanboy whining about two critical SJW posts and a bitter Twitter comment.