Re: Floor Joist Structure Compromised...Possibly ???
I think OP is stating that the hole was drilled down vertically and hit a double joist instead of the bay between joists. So the damage is minimal and not structurally significant, IMO. Unless he was using a 3" bit.
As far as cable installers knowing what they are doing? Give me a break; one of them drilled up through my sister's PVC shower pan liner! They had to pay for replacing the liner and the tile.
Remove not the ancient landmark, which your fathers have set.