There's no reason there couldn't be alien artifacts on the moon.
In fact, that's a perfectly logical place for aliens to have put them. We would find them shortly after we had developed space travel, and they would keep indefinitely in that environment. That doesn't mean there ARE alien artifacts on the moon. At any rate, if there are such things, they will be found by people with spaceships or telescopes, not on the internet.
It doesn't take a degree in science or the heart of a skeptic to realize that if Apollo had found any evidence of alien habitation of the moon we would have had permanent bases on the moon by 1980, defended by missile batteries and marines. We wouldn't share those goodies with anybody, and we certainly wouldn't let anyone else stumble on to them.