I don't think I'd take that approach.
a 5-year-old isn't equipped to make that decision. Period. T's the same reason I find the notion of child "transgenderism" so revolting. Kids that young don't understand things well enough to make choices. Newsflash: This is why we have parents to make our decisions for us until we're old enough to do so ourselves.
It sounds a little like the parents want to let her go but haven't got the courage to make the call themselves, so they're putting it on her. Maybe I missed it but did the article say anything about this child's long-term prognosis? If she's got a chance at a full life, then I see no justification for letting her go in the first place. She hates hospitals? Well welcome to the club. Here's another newsflash: Nobody goes to the hospital for fun. It's a tragedy that she's got this illness and it sucks royally that she has to keep going there, but I don't see that aversion to the hospital as being reason enough to let her die.
I have a feeling there's a lot more to it than what's in the article, so maybe if we knew more I'd feel differently.
"He who takes offense when no offense is intended is a fool, and he who takes offense when offense is intended is a greater fool."
"Don't take refuge in the false security of consensus."