Thank you, Wiggy.
Indeed, the disconnection of mechanically linked controls is not usual.
I believe that it would add single failure critical points, which tends to be a certification issue.
But now, with active controls electronically connected (Gulfstream G500 and Embraer KC-390), that shall be possible.
The"priority takeover button" can meaningful in many cases, as a training flight. But I am wondering why no one ever tried to implement that before...