If they had pulled this stunt
after tickets had gone on sale, I would thoroughly endorse the waving of placards, the hurling of tomatoes, and the occasional perfectly-timed shout-out.
As it stands though--those who bought a ticket to see this incarnation of Fleetwood Mac are going to see this incarnation of Fleetwood Mac, and should just live with that terrible, terrible decision.
Unless they decide after the first concert to replace Christine, Neil, and Mike with animatronic penguins.