Fibrillation indicates denervation of the muscle. It indicates the state of paralysis. What about the results of his nerve conduction studies both motor and sensory for radial nerve paralysis. Moreover, perform the sensory, motor neurological examination for his upper limb. Note the strength of muscles around wrist and elbows and see whether it is distal or proximal nerve paralysis.EMG shows fibrillation potentials
Why do you want to prefer traditional physiotherapy measures over the other methods. Is there efficacy of other methods over the traditional physiotherapy measures? Movements are good whether they are trick or passive; but the basic idea is to preserve the joint range and muscle elastibility due to prolonged disuse. Regarding the use of electrical stimulation in the cases of nerve paralysis, there is still recommendation in the electrotherapy books. I don't think what an individual opinion of therapist irrespect of any reference have any importance but see what the books or references say regarding that. Some times there is lack of evidence based studies over a particular nerve paralysis and the physiotherapy methods; so that could be reason that you may not get enough support from the evidence based studies data.
So ROM exercises, IDC, massage and splinting is good to continue.
Kindly provide more detail of your clinical examination of your patient.