'you'll never win an argument with a med crew...' That's a fact, jack.
So- don't ever argue with the med crew, ever. This is where the '3 to go' rule works for you. Explain what's happening, what your plan is, and consider suggestions. A fair few of the med crew suggestions can be explained away. If it can't, then you allow the crew member to abort the flight and you document that. You will lose some easy flights for imagined issues, but that's not your problem.