It's not meant to be "serious philosophy". He's not presenting the ideas in the book as being literally true, he's just provoking the reader to look at the issues in the book in a different light. Forcing the reader to consider alternative hypotheses, if you will.
Except it's a serious case of privileging the hypothesis. Pulling bullshit out of thin air != considering alternative hypotheses.
God's Debris is for people who "enjoy having their brain spun around in their skulls." I think I can safely assume that this descriptive of a larger proportion of LessWrongians than the average population.
Without going too far into depth, I will say that it is one of the more enjoyable reads I've had lately, the philosophy the main character espouses is coherent and astoundingly seductive in it's simplicity - even as it requires you to tilt your head and squint a little to see it.
Scott Adam's God's Debris