Seth makes an important point here in referring to the older baby boomers having some characteristics that have not traditionally been associated with old people, and hence his conclusion. 

Psychographics (open vs. closed) are way more important than demographics.

Source: Seth’s Blog: Marketing to seniors (open and closed)

I would adjust the statement to say that psychographics are essential to understand the impact of demographics, and how to think about the segments, including old baby boomers, otherwise know as “Cranky’s“.

The point in my simple view is that methods of assessing demographic shifts must take into account the psychological profile of each segment, and old assumptions are not adequate.