I too, think, that we should not make too big a deal about it.
For our Grand Poobah, FB is a means of promoting his musical activities (the band has its own FB page, too) and an outlet for his political opinions, which is fine. Political discussions, in general, tend to become a drag on forums. I believe most of us are glad that we do not have that here.
I like the "break glass in case of emergency" comparison, and I too, do not see the risk of moving any discussion there, as I, as a moderator of that group, would clearly state that the function of that group plainly is too have all forum members under one umbrella for contact in case of ...... just like a mailing list.
This forum is for exchanging and discussing info and opinions, FB would be just a place where you can find and contact some people and spread important news.
He probably would, but could be too busy dealing with any issues concerning the board to find the time and post there. We're friends on FB, and I follow his activities there, like the post of photos from his tours, and saw the band perform in the streamings. I will have a look at his friends list. Perhaps that already is what I had in mind.