If he's just going to ride it on smooth or dirt roads, I wouldn't worry about it. There might be some tendency to buckle (never actually heard of it until now), but it's not a common occurence.

Of more concern is to get a tire/wheel combo that fits the frame/fender clearances, protects the rim well (fat, lots of air volume), and that fits the brake calipers. Might be able to get some good aluminum rims and build a set of wheels to modern standards. The original steel rims are not as durable as you'd think, despite being steel, and the spokes are rarely at modern levels of tension.