The reasons don't much matter as nobody else has to agree with them,the only thing that does matter is that the person who has them actually understands them.
Anyone of my kids could refuse all manor of things and if they understood the repercussions and thought process behind that choice I would defend their right to do it, but some decisions they make are clearly not thought about ( thinking dc2 the bacon roll and being vegetarian convo).
It would be interesting to see the order as its unlikely that mum has been ordered to get it done,its more likely she has been ordered to make them available for it or take them to get it something like that. I should think you couldn't actually order mum to do it and no where has mention of a HCP also being named.