This is a bit like calling a beautiful woman a ‘slut’ just because she was born to be beautiful.
I’m sure we’ve all encountered cretins that do that too though, unfortunately a great many of them end up in positions of authority.
You’re right though, the couple were using it as a big, pretty plant, not a drug, and likely as not few people would ever have noticed a thing interesting about it had the police not made a big deal about it. Also, like the reference, I was watching that film a few nights back! I wonder if the police, when they came to remove it, had to remove it… With… A Herring!! (Ni!)