Denying care is the default state. It's the basis of the Hippocratic Oath, "First, do no harm." I.e. the determination of whether a treatment is beneficial is made by comparing it to doing nothing.
In these cases, a clinician has already decided that care is needed. It is a third party, who is not responsible for providing care, that is making the final determination. This has little to do with the Hippocratic Oath.
It's also how first responders deal with feeling responsible if someone dies on them. They did more than nothing, so their presence improved the odds even if the result was the same.