I just skimmed the S&C thread about the merger issue.
Do the active admins/mods from the other site agree with you on this issue? If so, you could try to start a voluntary user migration with their cooperation. Have them post a "suggestion" that users should move to this site. To keep it orderly, enforce a tag of some sort for threads continued from the other site.
If/when the owner shows up, you can do a legit merger.
(This site is getting boring... not enough serious flat earthers to argue with)