I'm not sure you're ever too old. The big concern as you get older is controlling blood pressure. But, it sounds like he's in pretty good shape already, and fairly thick. If he's in good shape, BP is probably good, but it's still something to monitor. He needs to take his BP a couple times a day, and maybe talk to his doctor about BP meds even if he's borderline to being high.
Keep doses relatively low. Make sure his diet and training are squared away. Diet becomes more and more crucial as we get older. He may want to talk to his doctor about TRT before running a cycle. Or if he doesn't want to bother with the doc, he can just run his own TRT when he ends his cycle. At his age it beats trying to keep his gains with PCT. And he'll notice plenty of benefits from the TRT, too.