Well, I can see William backing this investigation. He and his mother were close and he went through a lot during the War of the Wales. I forgot the Sussexes will continue to stay silent, due to Netflix, even if it is indirectly. Privately, Harry can't be too thrilled with the BBC /Martin Bashir revelations.
I'd read years and years ago that William was furious with his mother after the interview, what she revealed about her affair(s), apparently he was cruelly taunted by the other students at school.