I don't think anything has confirmed Uatu belongs to Fox.
Regardless, Attilan was located in the Himalayas, Atlantis, the Arctic, and New York City. The Blue Area of the Moon was one specific place it was located, not the only place. I don't agree with it being integral.
That being said, it's important to break that down. If Uatu belongs to Fox, does that mean the Blue Area of the Moon does? After all, it was built by the Kree. It's featured in the X-Men and other books as well. It isn't inherently tied to the Watcher.