I think the incels are into intactivism because a circumcision is an unrectifiable loss. Incels are deeply attracted to events and actions that are unrectifiable. Think about all the robots on 4chan bemoaning the absence of mutual adolescent love. One can be a turbo virgin all the way into college at least and still turn out fine. Incels didn't (turn out will), and they didn't (get any tail in highschool); so that must mean that being a virgin in highschool is what broke them.

In a similar way, many intactivists (especially the r/circumcisiongrief types) blame their sexual inadequacy on their post-natal circumcision, rather than their own psycho sexual issues or their habits of completely monkey-wrenching their shit on the daily. To be absolutely fair, a circ will almost definitely negatively affect your sex life, and really, it's frustrating to have a completely pointless operation done to your meat without your consent, but I think intactivism is a heatsink its proponents fervor, rather than the source of the anger.