I was reminded by Alleywig in a forum post that the old Disguise plugin protected users to be teleported to. Since the disguise plugin broke some time ago, I forgot to look for an alternative. In order to re-instate the teleport block, I now simply gave all donators from Architect level and above the option to use the /tptoggle command (see instructions on the bottom of the User commands page) to block people teleporting to them. I consider the option by masters to teleport to users a security feature, so I do want to keep that an option for Citizen and below.
Further, I am looking into alternative plugins to re-enable the disguises. More to follow once I have found something that works and updated the command instructions.