What can be done about right wing incels generating negative publicity for movies before they are even released?

The best thing that the sites you mentioned can do would be to encourage Hollywood to stop making such shitty movies.

so these "organized incels" have enough power to stop women from going to the cinema.

Oh Good Grief.. Over dramatizing a bit?? Did you have this sort of problem with this before Trump came along because it existed you know??

Removing people from social media sites because they're hating on movies is a pretty terrible thing to do.

I get that it's annoying when people just hate on stuff, and I don't like the bad attitudes that people have towards other groups of people, but nobody should just shut other people up because they don't like what they say.

Sites like IMDb should remove reviews/votes prior to the release of movies, because these people are lying (unless they've seen an advance screening; I don't know how IMDb would account for that), but other than that, they should let people have their say.

Also, a movie having a low(ish) rating like 6.2 isn't proof it's being review-bombed. I was just talking with somebody about the movie Demonic, which has a 4.3. We agreed that this movie was better than that and should have a higher rating, but neither of us complained that it was being review bombed or that the rating was clearly a problem, we just felt it was inaccurate.

Make movies that don’t suck. That are focused on telling a story instead of pushing an agenda.

The constant crap about incels is purely liberal projection. You betray your own weak character.

Incels and the alt-right is not to blame. Sometimes, movies just do poorly. Barbie was a huge hit this year and the incels didn’t stop that from breaking records.

Oh look, a leftie snowflake who can't take criticism and demands censorship instead.

Is it possible for someone to dislike this movie? It doesn't appear that way.