Look mom, I'm on TV! 
A lot of the people here are explaining that they have not seen incel getting used in this way elsewhere on the site, or at all. I know from experience that incel is used quite often as a catch all for misogynists and people who don't have sex, so this surprised me quite a bit. Since I did not expect my comment to get this kind of response, I didn't look for any examples of this kind of usage, here or elsewhere.
In order to actually determine the usage of "incel" on hexbear, I used the search function to show only local comments sorted by new. I skipped past all the comments from this thread and the previous one, as they are not relevant to the common usage of the term. I only read comments containing the word "incel" in the past 2 months. Overall, I was actually surprised at how often "incel" was used as a descriptor for actual incels, I did not think there would be as much discussion there as there actually was. Because of the common usage of "incel" as a label for actual incels I don't believe it should be prohibited. However, there were also quite a few times where it got used as a general insult towards someone doing misogyny.
Examples (Spoilered for formatting)
Gross comment by hexbear user replied to by calling them an incel:
https://hexbear.net/comment/5774460
incel spotted lol
Non-hexbear user doing a misogyny and getting called an incel: https://hexbear.net/comment/5770128
Women are responsible for their dating choices.
You are an incel fuck off
Elon musk getting called an incel: https://hexbear.net/comment/5748812
The fact a hyper-divorced incel moron like Elon is our super villain is just depressing.
In fairness to this one, I don't know if this guy is actually an incel, or just a reactionary weirdo.
getting called an incel: https://hexbear.net/comment/5742119
G%mers are such fucking cumbrains like firstly everything doesnt need to exist for your gooning and secondly shut the fuck up about your porn preferences you fucking incel
There are two main uses of incel on this site, the first is targeted towards Gamers^tm doing Gamer^tm things. And while I am sure many of these people are actual incels, most of the comments about them are really just playing into the sexless nerd trope in order to insult them that way. A gamer complaining that a women wearing clothes in a video game is woke could be an incel, but is probably just a reactionary doing misogyny. Many of these gamers are either in relationships with equally reactionary women, or are willing to lie to less reactionary women to have relationships with them. The other main target is yoon, while he may get a lot of support from incels, he has been married since 2012.
Just to be clear, I am not supporting anyone who people are calling an incel. However, "incel" is being used to insult people based on a perceived lack of sex had by the person being responded to, rather than just insulting their misogyny. A few people in this thread have mentioned that they don't see incel as an insult for people who don't have sex, and while I would like to believe that, "incel" is a shortened form of "involuntary celibate" which is obviously linked to a lack of sex. As said elsewhere, this is not something we should be insulting people for, as I said in the linked comment, I think this falls into the same trap as body shaming fascists, where the main people hit by the insult are not the target.
Overall, I think incel is fine to use in reference to actual incels, but not ok to refer to general misogynists. As an example, a person posting on the incel website could be called an incel, but elongated muskrat should not be called an incel. As I said in the previous comment, this would be annoying to moderate, and there are probably better ways for all of us to spend our time.