He is. And his care for the audience translates to posting 10+ post threads to mastodon, a microblogging platform, because he cares so much. Instead of, dare i say, posting one toot with a link to his blog.
It's pretty much the same thing as using services that you can't self-host and fork. I won't spend time on any technology that I'm locked into using their app or a login. Is that pompous? I've used various services and technology that are proprietary, and invariably it's bit me in the ass because they have a captive audience.
I will never use a smarthome device that has to have a cloud account or would be bricked without an internet connection, because eventually it will be a brick because the profit incentive says brick it and get the marks to buy another one. That's the point of that comment.
To clarify, the pompous part relates to "devote my energies to building up an audience". But maybe it's because I devote my energies to shitposting instead. On the other points I can get where you're coming from.
He's a c-list celebrity and genre author. I generally agree with what he says and enjoy his writing, but I'd be surprised if any of his usual audience joined a platform specifically because of him.
Edit: I am surprised that some of his usual audience joined a platform specifically because of him.
I followed him from Twitter to Mastodon, even though he didn't exactly endorse Mastodon. If he were to endorse a platform I wouldn't think twice about joining.
Is that was he is claiming though? I read it as spending effort to get people to follow him there, i.e. posting and engaging on the platform to increase his visibility and number of followers there, when he could spend that effort doing it elsewhere / doing something else.
I am surprised that some of his usual audience joined a platform specifically because of him.
You're surprised that a privacy and security advocate and essayist with a large online following would have people who would take his advice on which social media platform is best for security and privacy?