Surely I do. The hypothesis that after a certain period of hypoxia under the normal body temperature the brain sustains enough damage so that it cannot be recovered even if you manage to get the heart and other internal organs working is rather arbitrary, but it's backed up by a lot of data. The hypothesis that with the machinery for direct manipulation of molecules, which doesn't contradict our current understanding of physics, we could fix a lot beyond the self-recovery capabilities of the brain is perfectly sensible, but it's just a hypothesis without the data to back it up.

This, of course, can remind you the skepticism towards flying machines heavier than air in 19th century. And I do believe that some skepticism was a totally valid position to take, given the evidence that they had. There are various degrees of establishing the truth, and "it doesn't seem to follow from our fundamental physics that it's theoretically impossible" is not the highest of them.