No way would I ever leave a sick pet for a vacation. And the thought of having it pts so she can go is appalling to me. I guess I'm a real sucker for my dogs but I could never even go away for a whole day and leave a sick dog...been there, Everything got cancelled and we stayed home. I can barely handle watching a sick dog when I'm at home, let alone think of leaving on vacation.
I think your friend needs to do some heavy thinking on her decision....I really feel sorry for the poor cat.