This is quite a chunk of baloney. Even if these scientists could know without doubt what happened millions of years ago to the evolutionary tree, it would not have an impact on what we know about how the human body acts now. Medicine requires knowing the latter, not the former.
Understanding requires knowing as much of the entire picture as possible.
Sure, a chemist could get by and make concoctions using valence tables and memorizing tables and such, but he'll do a much better job if he learns something about quantum mechanics and thus know why chemical atoms behave as they do.
Engineers could certainly build airplanes from empirical tests. They build better ones when they have a solid grounding in aerodynamic and structural theory.
Doctors have a better understanding of the machine they're studying if they recognize that the vagus nerve is located where it is because it started out in a similar place in fish a long long time ago.
Knowledge without doubt about evolution isn't necessary in a medical doctor. Understanding a basic principle of science is.