Can you get a picture of his belly? You'd be able to see the intact pom if he is intact, or either no pom or a deflated pom if he is neutered.
Usually a bald spot would be a good indicator, but some males have smaller bald spots naturally, especially if he isn't around any female gliders. I have one intact boy who is 10 months old and has only a tiny sliver of a bald spot on some days...other days he doesn't have one at all. He's not a big scent marker, and I never see him rub his head on his cage mate, so I don't think he stimulates it enough. He does have a chest scent gland, though