This just quacks me up!At least you won't have any trouble locating an Xmas present: Duck Tape! (Walmart actually used to carry Duck brand tape!)
Suggestion 1 - It's a lame excuse. Just nod your head and agree that skiing is impossible for people with duck feet. Too bad.
Suggestion 2 - Get involved with Special Olympics and get him to try Mono Skiing. You've got to be a real man to have perfectly functional legs and let someone strap you into one of these contraptions and turn you loose on a slope. When I did it, they used duck tape to lock my feet down. It was the most scared I've ever been on snow and I was on the bunny slope. After that experience, even if he chooses not to ski, he'll have enough respect for the athletes to volunteer for other support duties.
Suggestion 3 - Have him try skateboarding and roller blading. If he can roller blade - he can ski. If he likes skateboarding better, he should try snowboarding. If he likes blading better, he should try skiing. If he likes neither, buy him a used couch and let him use the duck tape to repair it.
Suggestion 4 - If he's going to try skiing, then get him custom fit boots. It's possible he might actually need fitting, but at least you'll be taking away an excuse. But slip some duck tape in his boots just for a laugh. Get his poles, skis, gloves, etc too.
Duck feet are pretty common. I've got them and I ski OK.