I never argued otherwise, and it's besides the point. It doesn't change the argument for or against the notion that 'Northern AA voters aren't feeling the Bern', so it's irrelevant.
If the population size of AA voters is low in a given state, and there's accurate data to suggest that the majority of AA voters in states with low populations of African Americans vote for Bernie Sanders, not only would adam's statement be wrong, it would also suggest that there is some fundamental differences in the circumstances between these populations of AA voters.
Furthermore, we're still talking about polling at this point, which is subject to change. If Bernie closes the gap between him and Hillary in Michigan, you can expect those margins to shrink for the AA voters as well, even if it is because their vote is so lopsided. In other words, if Bernie closes the overall gap in MI, it will be because he made inroads with the AA voters there, and they would be certainly 'feeling the Bern'.