She doesn't have to force them not to leave.

Merely giving a televised speech that she respects the will of the people, but hopes they will take into consideration here years of experience and view it will be dreadfully harmful would have probably nudged a no. I know she normally does not comment on politics, but I also thought it's not out of the realm of possibility she'd pull a Silent Bob and speak up briefly when it is deeply needed.

Again I ask: what is the point of the monarchy, if they do not step in as some sort of check on the legislative branch when things go off the rails?