If it was to try to prevent the board becoming a useless vestigial organ incapable of meaningfully affecting the direction of the organization, it sure looks like they were right to be worried about that and acting on such concern wouldn’t be a mistake (doing it so late when the feared-state-of-things was already the actual state of things, yes, a mistake, except as a symbolic gesture).
If it was for other reasons, yeah, may simply have been dumb.
If you're going to make a symbolic gesture you don't cloak it in so much secrecy that nobody can even reasonably guess what you're trying to symbolize.
Yeah, I’d say they expected it to actually work. They misjudged just how far to the sidelines they’d already been pushed. The body nominally held all the power (any four of them voting together, that is) but in fact one member held that power.
If it was for other reasons, yeah, may simply have been dumb.