If the users have ModifyTicket rights in the for a ticket, the ModifyTicket rights documentation says that they also need SeeQueue and CreateTicket rights in the destination queue in order to move a ticket. If they have those rights, then it looks like they be able to move tickets.
The granularity of what ModifyTicket right lets people do is something I’ve mentioned before.
I guess if you wanted them to have ModifyTicket rights for other purposes but ban queue changing you could make a local copy of /opt/rt4/lib/RT/Ticket.pm and then tweak the SetQueue function to require more than just ModifyTicket (ie check if they are an admin, in a group of people allowed to set the queues, etc).