I'll confirm that no male in my basic put on significant muscle. I'd say on average weight went down a couple of pounds for the males. We did have some female soldiers go from barely being able to do a push up to a fair amount of muscle but they were starting from a much different place.
I'll not say 25 pounds is impossible for a trained athlete who has slimmed down and has a solid frame to work with. But his body fat is going to be up and he'll probably sweat out some of the extra water weight pretty quickly into the season.