Well, as a para, I have often thought about but never took 'roids. One of these days, when properly prepared, I will. If he takes them, sure his upper body will grow and he might get some slight mucscle growth in his legs. However, the Central Nervous System will not benefit. If he is trying to use them for his upper body and some general bulking, then best of luck. If he still thinks he can "will" himself to full recovery, he needs to adjust his outlook. Gear won't heal him, make his legs more functional or make him happier.
Aug 30th will mark 20 years that I've been a para. I really can't remember what its like to walk. Even though it's a different life, your relative can still have a very full one.
Maybe 6 months after getting out of the hospital, I asked one of my docs for a prescription for some weight equipment. He told me to stretch and lift books instead. Naturually, that answer was not acceptable. If your relative has muscle goals, tell him to go for it.