Just let it be, OP.
At our old place, the cable junction box for our cul de sac wasn't locked. We've always only had basic cable, so I remedied that situation by removing the trap. The difference between "basic cable" and the next tier up is that they install a small device on the line that filters out the channels that you aren't supposed to have.
Shrug. I'm not going to lose sleep over it. Not quite the same as the OP though.
Once when we got our cable switched to a new place, the tech just didn't bother to install a trap. Should I have called to tell them their mistake? lol.
The trap in this place is up on the pole, so it's not like I'm going to grab my ladder and climb up there. But if they practically invite it, I'll oblige.
IMO, this type of theft is an order of magnitude less unethical than even downloading software or music. I doubt there's a single person on here that can say they haven't downloaded illegal MP3s or software.