Fly a twin without endorsement - No!
Why the great opposition to flying a twin when not endorsed? Those who think this should not be done are demonstrating that they are not very good at weighing risk.
I assume the opposition is based on the notion that the twin may go assymetric.
But, the question is NOT whether a non-endorsed pilot could handle an assymetric twin;
The question is whether such a course would be "safe" in the context of a mercy flight. Given that the person will likely die without the flight, then the answer is a resounding YES.
Think about the probabilities of the two events.
The twin going assymetric? A chance of about 1 in 10,000.
The person dying? A chance of about 1 in 10.
On those odds, I would be more than happy for a non-twin endorsed pilot to fly a twin on a mercy flight to move a family member of mine that would likely die if not flown.