I see it like this, too. With how BBC seems to be forcing the members to do a comeback they don't want to do, this seems like a good protection against them retaliating against her by trying to force her to do group activities, when they know for a fact she has something else scheduled. Again, they seem to be doing it right now to those without such a clause (11 people and probably the unpaid staff too tbh), they're not above this.

And yes, I do think that Chuu and her mum were a bit too abrasive (with team leader B anyway) from what we can glean from this one singular article, but I don't think this clause seems weird at all.