My cat would live up there. We have a curio cabinet by the front door and the top of it is her spot. She likes to hang out there, silently judging us and chases the shadows from the nearby window.
If he wasn't supposed to be there you would have gotten cabinets that go all the way to the ceiling or no way to get up there. Now he has a way up there and is those supposed to be there.
I don't have to worry about that kind of stuff with him or his older brother too much. It's the youngest one that paws at stuff, he's very curious but thankfully hasn't figured out how to get up there.