I used to be a fervent anti-royalist. Now I'm just an anti-royalist. Once I might have fulminated, now I shrug. Trying to topple the monarchy is like shying at a coconut that has been nailed in place. People will go on loving the Royals no matter what.
And to be fair, it wasn't just the Royals who had unenlightened views about the mentally disabled. We all did. Only if we expect the Royals to give the nation a moral lead (which is absurd- though it's part of the job description) can we really get all worked up about this particular example of them doing the wrong thing. They behaved as most of us would.