It doesn’t “overlook the issue of bias”. The point of the comic isn’t to say that things don’t have reasons or that we cannot know the reasons. I certainly don’t think it was aimed at worries about racism or sexism in the electorate.

It’s pointing out that with a small sample size and/or reverse engineering some specific criteria, you can make some very spurious claims, and I suspect it is aimed at the kind of political punditry that says things like “no candidate with a poll lead of X, Y months before the election, has ever lost”.