it's not that asexuality is a choice, but the way the terms incel and "involuntary celibate" are generally used presupposes unfulfilled desire and resultant sexual frustration, with "involuntary" referring to external limitations. One of the more commonly cited definitions is an operational research one from
Donnelly et al 2001, "
one who desires to have sex, but has been unable to find a willing partner for at least 6 months" -- I think that's also in the sticky here IIRC.
Oddly, one of the more in-depth discussions on the semantics of "incel" can be found in the deletion talk pages of wiki, as the incel articles have been created & subsequently deleted 4 different times between 2006 - 2015... e.g.,
https://en.wikipedia.org/wiki/Wikipedia:Articles_for_deletion/Involuntary_celibacy_(4th_nomination)
Idk why someone who's asexual would want to consider themselves incel if they're not sexually frustrated.. "incel" is not exactly an endearing term and there are active campaigns across the intarwebz and IRL to try to cast the community as a hate-group. An asexual/hypogonadal/low-libido individual would also have limited capacity to empathize with the resentment/edge here due to the
cold-hot interpersonal empathy gap problem (same reason why most women have trouble understanding the anguish of chronic sexual frustration).
https://www.reddit.com/r/asexuality/ is probably a better place for an asexual