I would say let him workout, see if thats what he really wants to do, I would think if he thinks he wants to get big then he would have wanted to do it long before now.
If he can't hack it naturally then forget it, he's probably going to do roids for a few months, then if he ever goes off he'll probably stop working out like a fat slob is my guess. It can't be the drugs that drives him, he's got to want it, let him work up to a full workout routine, stick with it for awhile, if he can get the diet and etc down then maybe he can consider it.
Just my thoughts, they have to want it, not just some pill poppin and expect to be superman after that.