My personal opinion is this is not a good idea. You’d be the first person out of thousands I’ve dealt with that I have heard considering this. Doing anything that involves radiated bone is risky for not healing properly or triggering ORN or other negative issues. While some may argue that this is a function of field of radiation and GY exposure, these dentists don’t know any of that. There are no other bone quality tests that can be done. This is all related to the loss of microvascularization in the bone from radiation which they are not going to see on x rays.

Orthodontic movement involves pressure die back of bone on one side and new bone growth on the other to granulate into the void. Radiated bone is not going to behave like normal bone and like young bone where it is the most adaptable.

If they are so confident, ask them if they are willing to accept the liability for damage to your bone if this all goes south. Note that for you and them that liability could be a fibula free flap surgery if ORN is an outcome of this idea.