And if someone has many sexual partners, they are not incels.
Ergo, what I think the article means to say is "extreme misogyny probably not caused by being an incel".
I can understand the assertion, though, that being a shithead to women is about trying to look tough, be an alpha Chad, seem independent and incapable of emotion (like the main character in grease or so many teen movies of yesteryear). It's just easier to spread online now.
0. All of OP's submissions are from this researchinenglish.com
1. Link to the actual paper: https://psyarxiv.com/wsvq8/
2. It's pre-print.
3. It's based on a survey (self-reported).