You're right, of course it boils down to more than that - it was jokey oversimplification. It's one of the more concerning things about this virus - 4 months ago it was a lot more likely that this would be a high voter turnout election. Now who can be sure?
That said, as much as folks on this forum like to boil voters down to "definitely with us," "the blatant enemy," and concern trolls - there is a population of voters who haven't made their minds up, and they are important to elections. While the senility issue is obviously not the only thing motivating them (hopefully not even a significant one), how each candidate comes across on this subject will have an impact - already is having an impact. In a potentially lower voter turnout election, we need everything we can get.