Could he be more carbon neutral in releasing a book, than making it ebook-only, which he seems to have done here?

Look at his Twitter, he owns cars, boats, a multi-storey house on the Gold Coast without any solar panels

That's a ridiculous thing to worry about. Individuals, even the ones with boats and houses, aren't what's driving climate change. All the time and effort you spend playing "Solar Panel Police" would be much better spent attacking the environmental harms caused by industry. Could this guy afford some solar panels? Probably, and sure every little bit 'helps', but it seems so petty to bitch about this one guy when there are so many others causing problems that are so much more impactful.

He gloats a lot on Twitter about this stuff which is why I unfollowed. It went from great content to soso content and lots of gloating.

Seriously the amount of gloating is kind of absurd. Here in Australia we have "tall poppy syndrome" where we cut people who are above us, but this guy loves to brag about the crap he has.