I don't think his point is that the you shouldn't follow these rules though. Surely nobody would think you shouldn't proofread? He is just stating the rules ironically with an embedded example. Most of his rules are fine.

Yeah, he's obliquely endorsing the rules, most of which — certainly the ones about infinitives, passives and negation — are moronic.

What I take from it is that those points aren't important at all.

That's surely hyperbolic, because nobody would think about completely ignoring them. But they certainly do not make any text great, and they shouldn't be followed on the cost of something more important.