That's an interesting argument. I have a friend whom I've argued about this with on multiple occasions. She thinks PPM is a flawed technology because she argues it's cume based. To me, this doesn't make sense, because if that were so, at the introduction of PPM, you would have seen a sharp drop across the board for any talk format. Any kind of talk, whether that be political or sports, is going to have a much lower cume than the average music station with the same AQH share.
Her other criticism of the technology is a bit more warranted, though still probably less so than she thinks. That criticism is that you could be forced to listen to some station that you really don't like, and the data would show you as a heavy listener of that station when you're really in an environment where you have no control of what's being played. Again, I'm not sure this happens much, but at least in that instance, I can think of someone who this could be an issue for. Last time I talked to this person, she had been working in retail for some time. While she had moved on from this particular employer by the time I left the area, I know she worked for one particular store that played 95.7 or 106.9 most of the time. Her primary has been C89 for years, but the data would show her as a P1 of 95.7 because that's what her workplace played. Given that many local retailers don't play local radio these days, I would think this is less of an issue than it would have been 20 or so years ago.