It is not uncommon for such transactions to be negotiated in confidence. ISOC Board members probably knew about it but would have been obligated to not disclose to anyone without need to know status.
That's understood. But in a nonprofit such major decisions -- substantial asset transactions, bylaw changes, etc -- are typically ratified by membership after negotiation, in this case the various electors of the ISOC Board. In many cases such oversight is baked into the bylaws.
I see nothing in the news at hand to indicate that the transaction is subject to any such ratification.