Simple enough to make a handlebar clamp and attach a mounting bracket to that. It need do nothing to support anything, it just needs to be a mooring point for a bracket that interferes with removal of the screen.Yes, that does sound like a potentially good solution.
The anti-theft brackets that are being made for GSs (which are fitted with exactly the same TFT screen) are bolted to the bike using the many available locations on that bike, but because the R1250R is a naked bike it will be difficult to design an external security bracket as it has nowhere to be mounted to.