It's not a non-sequitur if you follow his chain of logic, which is focused on improving outcomes, and not simply on expanding voting for its own sake:

1. Are voting rights missing? (Gather information) 2. If they are missing, would adding these specific rights improve the quality of voting? 3. If the answer is no, then the fact that certain rights are missing is less relevant.

You clearly disagree with him, because you see expanded access to the vote as a good in and of itself. That's a tenable position, but not everyone agrees with it (I certainly don't), and so it's good to see where others are coming from.

tldr; Some people think that more voting always = good, some people are more consequentialist.