It would be good to get confirmation on this as it contradicts statements upthread saying the board, in USA [though I'd expect it might be specific to a stock market], decided on behalf of the shareholders (to whom they have a duty).

Someone noted the UK position required shareholder assent, which sounds like what you're saying here.

If shareholders vote that sounds 'fair'. If the board decided and shareholders are obliged to go with it as that's how shares are [in some particular jurisdiction/market] then it being fair seems of no concern to that system (as a sibling content intimated).