Muscle relaxants have been added to Bier Blocks for many years in small doses with big effects. Once the tourniquet is up there should be no significant clearance of the muscle relaxants out of the compartment.  The addition of more antibiotic, anti-inflammatories, or muscle relaxants to the other side of an inflated tourniquet makes no sense.
The rare reduction of a prosthesis or joint has been greatly assisted by brief use of muscle relaxant in my practice but the surgeons layout of the butt joints on bone has never improved with relaxants.
The real issue is what possible good does the surgeon achieve by distracting his care to a pharmacology about which he has no knowledge or liability. The behaviour needs to be extinguished and the nerve stimulator put away.