I'm not sure they can now. The Guardian and Times have both named them overnight too, as have multiple media outlets overseas. They should get lawyers involved.
I see Scobie is now moaning about "irresponsible people" sharing the names online, while 'a friend of' Meghan has claimed to the Telegraph that it wasn't anyone from her camp who briefed him on the names and she never intended them to ever be made public. Thus confirming the names.
I honestly think there is no coming back for MM and PH from this in terms of the UK's public perception. We all know how devastating it can be to be wrongly branded racist in this day and age - if you're going to throw out such damaging accusations, at least have the courage of your convictions and stand by them.