Once acquisition happened those stakes were no longer ninja-minded
Sorry I can't agree on this point, particularly in so far as the transaction was described as acquisition of the company. I fail to see how the identity of the sharesholders of a company, or a change in the list of shareholders, changes anything about a particular block of stake that was ninja mined to support development of the ecosystem.
If the stake alone was sold (not that there is any evidence of this), then I would think either there would or should have been disclosure of any baggage associated with the asset (whether legal, reputational, unrealized risks, or pertaining to strategic business considerations surrounding the use of the asset). If not then it seems like something for the parties to the sale to work out.