If you think that he's the only RI or CT resident, with a Mass commercial license, loading his boat from RI, CT, NY or EEZ waters and bringing them to a Mass market, you're dreaming. He's the tip of a very large iceberg.
Do the math--at $3.50 a pound, a Tues-Thurs commercial limit can be a grand or more, and a $450 fine is well worth the risk.
Now if the fine was $450 per fish.........
And Mass. DMF has acted in the past to forfeit gear, and even boats. But unless they see him coming from out of state or Federal waters, there isn't a damn thing they can do on an open day. Multi-state enforcement is tough. RI isn't in any better shape financially than Mass, probably even worse, and I can imagine that DEM's budget is stretched to the max. They have to patrol where and when they can.
And you can bet your bottom dollar that someone dimed this dude out. He shot his mouth off to the wrong person, or maybe a pissed off Mass. commercial saw him operate the hidey-hole at the dock.