Remove the teleportation block from the brig.

[Grek]

Teleporting prisoners out of the brig is a thing that can happen, and there's pretty much nothing that security can do about it aside from giving a constant death glare at the telesci console at all times. There are ways to prevent plasma fires (such as not being near them or liberal application of fire extinguishers) and the stealing of the AI modules doesn't do a whole lot of damage unless the initiator of the heist is able to get into the upload to begin with. Also, plasma canisters and AI modules are static, innate objects, which are easily stolen and returned.

Security has access to forensics. Lift the prints off the teleporter. Or put a tracking implant in important prisoners. Or keep an eye on the radio, because how is the telescientist telling the prisoner where to stand to be teleported?

The problem with plasma isn't people stealing plasma cans. If you have access to the teleporter, you have access to toxins. The problem is teleporting the plasma to places. Avoiding plasma fires is hard if research uses the teleporter to teleport an open plasma can to you, followed by a lit welder.

The problem with being able to teleport into the AI room isn't stealing the modules, it's: A] using the teleporter to grab a module then teleport yourself into the wall behind the computer to upload a law and B] teleporting yourself on top of the AI and beating it to death while it can't do shit to stop you.