The internet gives a mouthpiece to many, many people; not everyone's opinion should be considered with equal weight. The essay's author uses the example, "EARTH HAS 4 CORNER SIMULTANEOUS 4-DAY TIME CUBE." It is content that someone put a lot of time and effort into. How should I use the ideas and world view found in the timecube website to forge my own?
Probably not much. That's what I equivalate with "taking seriously," and a "serious public intellectual" is someone whose opinions I would probably consider when forming my own.
I don't think the author is tearing PG down to try and oust him from his material wealth; just saying, maybe what he writes in his essays shouldn't be taken as seriously as some of us thought.