My guess would be because the “we’re trying to kill her” thing is an extreme aberration of the regular order of things so as soon as the narrow window where that was somehow okay is closed the default practice of trying to help people kicks back in. Especially once she’s in the hands of actual medical practitioners who take their oathes seriously.

I doubt the medical staff would participate and the idea of an execution is that it’s supposed to be quick and painless.

The same question has crosses my mind too though. Seems super bizarre to decide to do something like this and then pivot to life saving critical care as soon as you fuck up. I read that the people they have to obtain IV access as not well trained so the IVs tend to infiltrate (leak into the subcutaneous tissue) leading to only a partial dose being delivered to the bloodstream.