Bowmouth
Contributor
I was once criticized on a dive-boat in Florida for bringing rubbish aboard and putting it in the bin.
Often over time rubbish on the reef becomes new habitat for creatures. Once creatures have transformed the rubbish into a "home" it's (often) better to leave it as it is. In Lembeh Straits (North Sulawesi) you find the best creatures living in old shoes, empty paint cans, discarded oil filters and other trash.
Maybe on the boat in Florida your DM was worried you picked up trash without being careful and selective. Or maybe he just didn't like a smelly bin.