The best course of action is to setup a country called 'Diversityland' where all are welcome.
Not a normal nation that morphed into diversity through subversion; thus being accused of holding on to nationalist sympathies when it goes awry - but a new nation where it is made explicitly clear from the outset that all residents are multicultural lovers.
All multicultural fanatics will be given a ticket to Diversityland as soon as they begin to pipe up. I've money put aside for Ronit Lentins ticket already.
All Diversitylanders hold the right to return to their country of origin should they change their mind - I have no doubt their boats and planes will be fully functional should the day come when they choose to escape paradise.