They did notify everyone. They did it after firing which is within their rights. They may also choose to stay silent if there is legitimate reason for it such as making the reasons known may harm the organization even more. This is speculation obviously.
In any case they didn't omit doing anything they need to and they didn't exercise a power they didn't have. The end result is that the board they choose will be impotent at the moment, for sure.
Like, nobody is going to arrest you for spitting on the street especially if you're an old grandpa. Nobody is going to arrest you for saying nasty things about somebody's mom.
You get my point, to some boundary both are kinda within somebody's rights, although can be suable or can be reported for misbehaving. But that's the keypoint, misbehavior.
Just because something is within your rights doesn't mean you're not misbehaving or not acting in an immature way.
To be clear, Im not denying or agreeing that the board of directors acted in an immature way. I'm just arguing against the claim that was made within your text that just because someone is acting within their rights that it's also a "right" thing to do necessary, while that is not the case always.