I don't think he is going to be a villain at all. He was an odd character at times, but I don't think he would be evil, he knew the evil of the mask, but I think he would have the control not to be a puppet. I do not see him being evil, a bit creepy at times, but not evil.
He is weird, creepy, and probably a stalker, but that doesn't make him evil. (He also might be able to bend time and space so he would be able to know the moon would fall [this also may be how he got to Termina])