Wanting to get paid for a book he wrote is a bad thing?
I get it - from each according to their capability - to each according to their needs. Sound familiar?
Nobody said it's a bad a thing. The bad thing is claiming he wrote it to help people without mentioning the monetary motivator. This is dishonest, end of story.
Wanting to help people and charging for it are completely separate topics. There's absolutely nothing dishonest about it.