The museum should have never kowtowed to the angry rabble to begin with. Once you apologize, it is hard to make a boundary. You’ve exposed your belly and it will be lanced.
Apologizing presupposes that you are dealing with reasonable people, who can be coaxed into an actual discussion and who can even agree to disagree once they have made their point. Who will see your extension of a hand as a token of good will. Not so. This group has an agenda. They won’t stop til they have destroyed the life of this artist. They are in the same league as the religious fundamentalists who tried to destroy Mapplethorpe. The only acceptable answer to this censorship is – NO, and NO again. Don’t even entertain them as serious thinkers, they are not interested in art, they are interested in the destruction of creativity and individual, inspired voices.