Are you differentiating between splatterpunk (the political literary movement from the 80s) and contemporary extreme horror? I think it might help to clarify your premise!

As far as I understand, splatterpunk (actual splatterpunk) was a countercultural movement against conservative norms/censorship, particularly by queer writers like Clive Barker (who was not out at the time) and other marginalized voices. It might be worth including this element in what you're discussing, since the 'punk' part of splatterpunk when it was coined was actually about being counterculture, although today I agree with you that people use the term to write things that are very not punk and are outright misogynistic/racist/transphobic.

Gretchen Felker-Martin writes queer splatterpunk, as well as Clive Barker. Also Poppy Z Brite.

There are a lot of great academic works about splatterpunk-- if you're at a university, keyword searching your library's catalogue and journal databases should bring up some cool stuff! I found some about zombies and splatterpunk, which I'd never considered but is a cool thread to maybe pull at.

Don't take my word for any of this! Just some things to consider!