I think all their visas should be revoked, not just the imams. Particularly the ones who are here illegally, either on expired visas or that came across the border?
at some point Islam as a religion must be visited.
It seems more a tool for spreading dessert tribe fractionalism than as a tool of spiritual enlightenment.
It is a serious issue since there is a minority of believers who seem to function as "useful idiots" to the reality of islam's actions.
Revoking tax exemption to the mosques that brought them would be a good place to start.