It’s not possible to restrain a holoparasite user, because the holoparasite will kill anyone before they can apply the restraints.
First you need to make holoparasite turn off when user is in critical status, make the holoparasite get disabled instead of user getting ashed, with a generous respawn timer (10 minutes or more) for the holoparasite player so they are not totally out of the round. Then you can start contemplating how to restrain the user.
But really ideal solution would be removing holoparasites as they are just murderbone unstunnable deathmachines that bypass all ranged/melee combat limitations and can spam their attacks insanely fast without ever running out of any resource. It’s a really limited interaction when the only option is to kill them as there’s no downtime, no disabling, nothing but brute force.
This kind of “remove every antag who hurt my feelings” mindset is why some people are leaving this server already. For a lack of better words, git gud.