One might assume that the board has known 'whatever they know' for quite some time, possibly discussed quietly behind the scenes, which includes them scouting out potential interim CEOs.

Then when it becomes clear that negotiations won't solve the problem the board drops the hammer and lets the other side make their move. If they act professionally and like adults, well, maybe there's room for negotiation after all.

If, on the other hand, they do weird childish shit, well... guess not. In with the new guy!