Phils wife and daughters support of him has nothing to do with 'family loyalty'.
After Jeremy Clarksons article on Meghan Markle was published and uproar followed, his own daughter publicly condemned her father.
THAT is what family loyalty looks like.
It's holding your loved ones to the values you believe in. It's calling them out when they cross the line. Its refusing to defend them when they do wrong. More than anything, it's not compromising on your own principles just to stay on good terms because of genetic loyalty or what you feel you owe them. By condemning her father's column, JC's daughter proved to the world that he'd raised a gutsy, independent-minded girl, so perhaps he wasn't the misogynistic monster that his critics made him out to be.
Phillip only condemned his brother, at the very end, because he had no other choice.
His wife and kids do not remain through loyalty, because there is no loyalty in letting the people you love most act abhorrently. They are there to ride on his coat tails for an easy life.
(Just to add, I feel that the editor should have taken more of the flak for not rejecting the opinion piece and telling JC to just reword it to something less graphic. Woulda save a whole lotta bother!)