Snorting it has a higher BA, he could gauge it's potency by smoking it first. But it's his first time so you're right he should definitely smoke it, no matter how poor his technique will be, probably safer that he waste some.
Pretty sure that in terms of health consequences inhaling that vapor is worse for you than waterlining though, after you're accustomed to the drug.
IMO, if could get my rocks off with that little oxycodone I would have no business doing heroin.