According to the screenshots, Ghostbusters1234 didn't claim he built it. Are you sure you are not just being overreactive? The building's not even yours, this is Incinerate's deal.
Upon you start hosting a building on multiplayer, it is not yours anymore. You cannot stop users from saving buildings and using it on their servers. You are powerless to stop them and there's nothing you can do about it.
Stop being whiny about people stealing builds, if you don't want anybody to use your build, just play singleplayer. kthx