Welcome aboard. I can definately tell by your first post you'll fit right in here.
In all reality what can you do? You can't make the slob see through ethical eyes. More then likely your words would fall on def ears. I hope this guy dosn't hurt himself or IMO worse, wound a deer becasue of complete lack of respect for wildlife. Should this JA get a non lethal hit on a deer it may change his feeling to the whole situation or it may not. I know I carry the one deer I wounded and didn't recover with me every time I enter the woods. I think it has a lot to do with why I'm the hunter and person I am today.
We can't control other but we can lead by example. You may not have spoken up but I have a good feeling that you're a leader.