They said this in the article, but it doesn't make any more sense here than it did there. If unemployment remains the same, where are these 'better' workers coming from?
One possibility: unemployment is defined as someone who is not working AND actively looking. If wages at McD went up to $15 an hour, some people who were not actively looking may enter the workforce.
That is certainly true. However, if I had said 'employment is not decreasing' instead of 'unemployment is not increasing' it would still have been a valid critique without being vulnerable to that response, however.
Yep. FYI economists use the term "labor force participation rate" for this concept.