It is relevant in some cases, including this one, for the following reason: The main argument used in favor of evolution, both here on FR and in the wider society, goes like this, "EVERYONE believes in the theory of evolution, except for a few toothless, barefoot, hillbillies who are too stupid to understand it."
The number of people who believe in evolution becomes a relevant issue in that case. And the fact is, most people do not. Despite decades of coercive propaganda, you have not been able to make your case to most Americans.
Um, no. The main argument for it is that we can see it in nature. Google "bird flu virus mutation" for an example.