Because it is selective “free will”.
And anyone booing at the match today is essentially saying “Fuck the club, the manager, and the players”, as they all have said the booing does not help them and they don’t want the fans to do it anymore.
Not to mention booing serves no constructive purpose at this point. UEFA already know how the fans feel about their treatment of the the club in the past, the club has moved past it and are trying to no doubt affect change via direct influence at UEFA rather than adversarial action, and booing just makes that more difficult.
Fans booing actively works against the goals of the club (and the players, based on what our own captain has said).
Not sure how much clearly fans could say “fuck the club, the manager, and the players” than still booing at this point.