Does anyone "expect" them to do these things? I suspect that if H&M said no thanks, not for us, we're going back to the US, they would be left to it.
Take a breath and think about it from their pov for a moment. It's Harry's grandmother, but access to the things he wants to do, to pay his respects have to be 'granted.' Following coffin etc. When they are granted these things, the press frame it in a way that reflects positively on the Official Royals, not them. Fab four nada nada. Will & Kate are the most gracious forgiving people etc. W&M have bern shamed and not invited to state funeral (because they're being humiliated and are undeserving being the implication)
Then once this is over it's 'You've done your bit, now fuck off back to America, you're not going to granted any more favours'
And Andrew not being invited is hardly comparable, if he was my Uncle I wouldn't invite him to pub trivia night let alone a state reception.
I genuinely can see the issues of M&H and do not like them, but I think the Royal Family have and continue, to deal with them in a way that makes them feel their backs are against the wall and is inflammatory instead of conciliatory.
And I can tell you I was a huge critic of M in particular and still am never gonna be a fan, but even I am starting to see it really can't just be all them. (Annoying hand-holding aside).