I am critical of the fact they chose to use the girls and didn't add Shang-Chi
I mentioned this already, but I'll say it again: Shang-Chi was there. He was tied and hung with the rest of them, to the left of and slightly behind Felicia. Perhaps you should look again? You apparently missed him, but he's there, getting slobbered on and threatened with tentacles just like the girls. Whether that was "gay or something" or not, there he was.
I took the step from 'attractive and vulnerable' to 'sex and (the suggestion of) violence,' or, in short, 'sexualized violence.'
Now here's where we're going to disagree. Because I feel that step is completely inappropriate, and I'll explain why.
Sex and violence are going to exist in almost any media work not completely bowdlerized to a child's level. Often in combination. So often, do crimes and atrocities and other unpleasantness, including diabolical evil. Does that make the stories themelves immoral or wrong? No. It depends on how the bad elements are presented. Who is committing the immorality, and against whom? Who is the reader supposed to identify with, and what are they intended to feel about the crimes depicted? Does the story imply approval of the immoral acts it depicts, or condemnation? That makes a huge difference in the moral tone of a story. If the intention is for the audience to cheer for and sympathize with the victim, and condemn and root against the perpetrator, then a story can portray all sorts of horrific evil and still remain positive in it's morality.
That's not how "sexualized violence" works. Instead of a tone of horror and condemnation, it glorifies the crime it depicts. It denigrates it's victims, and puts the audience in the position of identifying with the perpetrator and enjoying the use of the victims. It makes the violence itself sexually titillating. You're meant to get a charge out of it. And I'm in 100% agreement with those that condemn that sort of depiction.
That's not what's happening on this cover, though. You're not meant to enjoy what's happening to the heroines, you're meant to sympathize with them and hope for the best for them. You're meant to worry enough about them that you'll buy the book to find out if they end up alright. You're meant to find what they're being threatened with frightening and wrong, and hope it doesn't happen. The violence isn't glorified, it's condemned. It's depicted as a Bad Thing. The sex appeal is just there to make sure you care enough about the characters to worry about what happens to them. The violence itself is not meant to be sexually appealing, quite the opposite, and that's why it's not "sexualized violence".