I don't think there's anything wrong with family members being concerned, or visiting a sibling for a 'welfare visit' as someone has termed it.
I can imagine that AMW's moods may well fluctuate, and that his family may want to judge for themselves how he is. Given that photographers seem to be permanently stationed there, it would be difficult to do so without anyone knowing.
I haven't so far seen any real suggestion that the RF is trying to 'rehabilitate' AMW or bring him back into public life. For quite a while I have seen social media commentators suggesting that the RF will be making use of AMW's 'mental health' - not to bring him back to public life, but to create sympathy for him, as @TheAutumnCrow has suggested.
That's why I wondered in my first post why TS/AL are pushing this story particularly now. It may, of course, simply be because royal news has moved on from AMW a bit.