If that was allowed, it might save hundreds in the short term and doom millions in the long term.
Of course I'd do whatever it took to save myself or my loved ones. Anyone would. That's not a good basis for government policy.
(Also, being honest, the number of situations where powerful antibiotics now vs. at the hospital would make a difference and the people involve realize that and administer them has got to be tiny. We can't make policy based on low-probability hypotheticals.)