Oh come on, have you ever been around someone smoking pot? And I mean within like 500 yerds of them. The smell is strong and spreads. Even with just one person smoking I can smell it from the street all the way up into my apartment. I have no idea whether OP’s son was smoking or not, but I absolutely would not assume that just because the smell was strong, multiple people were toking up.
I hope that is not what happened. That would seem wholly disproportionate to me. Hopefully the OP will come back and update us.