Is the King gaslighting Diana's brother?

Buckingham Palace has said it doesn't comment on book releases as a matter of principle. And yet it has commented on a new book - from Princess Diana's brother - in a way that has sparked off a news cycle.
Earl Spencer claims in his new book that in a heated row with Charles in the preparation for Diana's funeral, the then Prince spat out "Rest assured, we'll forget her soon enough". The Palace's response: "His Majesty is mindful that the pain of fraternal grief can cloud reason, affect judgment and colour memory in ways others do not recognise, even many years after such a loss."

Why has the Palace chosen to pick this public spat? Why are the Royal family unable to go a week at the moment without descending into some form of internecine warfare? And should this sort of family squabble even be published in the first place?

Later, the EU's love affair with Canada has caused Donald Trump to sit up and pay attention. He's threatening to stop trade with Europe if it feels "hostile" to America. Mark Carney says that "no one is going to dictate our culture." So what happens now?