This is why I think Andre or someone who would know should chime in.
I'm no where near the most knowledgable person on the subject, but when I read that, I see you can't POSSESS lead shot for the purpose of hunting a migratory game bird.
Maybe I just take that differently than others (I'm no English major, which is why I wish they would just give an example) but my thought is that he does not possess the lead shot for the purpose of migratory game bird hunting. He has it for the purpose of hunting grouse. It's a fine line, but that's the way I read it. As I said, I wouldn't risk the ticket just based on my opinion, because I can obviously see why telling a CO "I swear, I have lead shot and I'm shooting geese, but I didn't bring the lead shot for that purpose!" isn't guaranteed to work.