Very difficult to say what needs to happen without seeing the guy. Understand your concerns though.

I would personally liase directly with his orthopaedic surgeon as to what he can and can't do. Usually the # is stable because of the plate and screw but can't be certain. If it is stable, you would think that weight bearing within tolerances is important for bone laydown. Making sure he stays out of pain is also important in a lot of ways - don't want CRPS!

Otherwise, as noted above, liase directly with the orthopod via phone or in person if possible to ensure exact rehab conditions.

Good luck!