I think the police are required to investigate if they get a call to 911 that hangs up. It could have been a person being murdered after all. (I think there was a case where the police did not investigate far enough recently in the Vancouver area and a woman died.) I think if the dad had answered the door when they knocked, he could have saved himself a lot of trouble, but there was no answer at the door, so the police had to go in and have a look.
I'm not sure why they were allowed to look around after they found out what the phone call was about. Maybe it was procedure (in case someone was being murdered.) In any case, I'm glad he got caught. I do not think marijuana is harmless, and anyway, why promote second hand smoke just as tobacco is being phased out? That makes no sense.
I am all in favour of milder drugs like alcohol, sugar, caffeine, chocolate . . . We do need to have some fun now and again. But when people insist on doing illegal drugs, I have to wonder what's going on, when there's plenty of legal stuff to indulge in.