Kotoamatsukami is a canon KG, and cannot be personally claimed. This also counts for Amaterasu, Tsukuyomi, Kamui and Susanoo, which all fall under the same category. If someone decided to put up a list on the Claimed List for any of these, they would essentially be saying that nobody else from that point on can learn them.
But the main issue with this isn't the above. It's the fact that the technique is literally "character control jutsu". Any use of it would pretty much guarantee a voiding, unless the victim of the technique is very misinformed about RP manners.
There's also the fact that it can be cast upon a large population upon the user's request. They can literally go to Konoha and say, "I'm Hokage." and everyone would have to bow and say "okay lol".
http://youtu.be/iKKUVtwaugk?t=5m52sI wouldn't consider the character control much worse than the abilities of the Tsukuyomi, if the tsukuyomi can cause permanent brain damage to a character, forever forcing the rp style to be changed as the character wouldn't be able to recover from that.
Tsukuyomi is a genjutsu, and people can fall into genjutsu if they aren't careful. Though if they're smart, they'll remember from ninja school how to detect genjutsu and release themselves from it. Tsukuyomi isn't as simple to break out of, but either everybody and (sometimes literally) their mother has the Sharingan, or know NOT to look a Uchiha in the eye unless you are one.