Hi,
As you say, Re can give an indication of laminar or turbulent flow given a number of assumptions which include incompressible flow. You could always work it in reverse: what happens to the airflow at Mcrit? How do you correct for the effects which are not accounted for in the calculation of Re? What Re do you end up with once those effects are accounted for?
I have never used Re in wing calculations but there may be limits to how far it will apply given the increasing dominance of factors such as shocks and their effect of the properties of the fluid.
It may be that your interviewers only wish to explore your knowledge of Re rather than achieve a specifically 'correct' answer.
Best wishes
AD