His problem basically is that the perfect is always the enemy of the good. Because Mastodon does not, today, solve all of social media's problems, it's not worth further effort. It's the easy hot take and there have been dozens, maybe hundreds of variations on this post on Mastodon lately, almost all of them with the implicit conclusion that it doesn't seamlessly replace Twitter, therefore the only way forward is Twitter. The same Twitter that was a service famously in search of a purpose for many years in the early days, with many pundits opining on its uselessness.