This is late, but do you remember how he got his mailing list off of HN? -He started an interesting experiment about starting a business from scratch, and planning to reach X thousand dollars of income per month in only a few months. "The Web-App Challenge" or something.
That was a very interesting project, so I signed up for updates. Not long after that, his e-mails started being mostly about selling ConvertKit to us, interspersed with useful(-looking?) articles. I can't help but feel like selling ConvertKit was his goal right from the start, and that the web app challenge was just a ruse to get us to receive his sales pitches. This is very clever, of course, but it's sleazy too.
ConvertKit is the thing he made as part of his "Web-App Challenge". Of course he's going to talk about it in his emails!!!
The whole point of signing up for the list is to see how he does what he says he's going to do. The emails are showing you almost EXACTLY what to do if you want to copy him. Would you prefer he put you on his list, then never mention the actual thing he's building?!
Could you try any harder to find something to complain about?