So .... you claim harm from Xenforo stealing your "Copy Twitter" logic - before you could get to it ?
So vB is allowed to copy Twitter and be "Twitter-like" but xF is not allowed ?
So the lawyers admit vBulletin copies other software such as Twitter. They directly say vBulletin is trying to be "Twitter-like".
If they condone making their software like another .... why wouldn't another software be able to be like theirs ?