He claims that the employment to population ratio is "nearly meaningless".
Because it was higher in the 70s than in the 60s and we all know the labor market was stronger in the 60s.
I'm not sure why a statistic becomes "nearly meaningless" just because it requires a modicum of interpretation and comparison with other statistics before drawing a conclusion. Maybe we might want to talk about female labor force participation?
He prefers the unemployment rate, which is also a good indicator and especially good in comparing the 60s and 70s because the denominator is the labor force itself so it's not going to rise simply as a result of secular changes in female participation. Fine. But it's hardly ideal for thinking about problems today since the unemployed also have this tendency to stop looking for work after a while.
You know what would be a good indicator...
...the employment to population ratio.