Because this is so politicized, I would go with a simple rule:
If he’s not dangerous enough to lock up and keep behind bars, he’s not dangerous enough to take and keep his guns. I would go further and say that even convicted felons should regain their gun rights as soon as they are no longer under the control of the criminal justice system. If someone isn’t safe to hold firearms, they should have been given a longer sentence behind bars.
Call it the Custodial Rule for Constitutional Rights Retention.
Only those authorized and responsible for providing for the personal defense of those in custody can deprive a person of their private means of self-defense.
Re #6: Thoughtful comments.