It is fair to say that Substack has had a dramatic week and a half or so, and I talked to their CEO Chris Best about it. The company announced a new feature called Substack Notes, which looks quite a bit like Twitter — Substack authors can post short bits of text to share links and kick off discussions, and people can reply to them, like the posts, the whole thing. Like I said, Twitter.

Twitter, under the direction of Elon Musk, did not like the prospect of this competition, and for several days last week, Twitter was taking aggressive actions against Substack. At one point you couldn’t even like tweets with Substack links in them. At another point, clicking on a Substack link resulted in a warning message about the platform being unsafe. And finally, Twitter redirected all searches for the word Substack to “newsletter.” Musk claimed Substack was somehow downloading the Twitter database to bootstrap Substack Notes, which, well, I’m still not sure what that means, but I at least asked Chris what he thought that meant and whether he was doing it.

It’s tempting to think of Substack like a rival platform to Twitter, but until the arrival of Substack Notes, it was much more like enterprise software. With Substack Notes, the company is in direct competition with social networks like Twitter. It’s shipping a consumer product that’s designed to be used by Substack readers. It is no longer just a software vendor; it’s a consumer product company. And that carries with it another set of content moderation concerns, that, after talking to Chris, I’m just not sure Substack is ready for. Like, I really don’t know. You’ll just have to listen to his answers — or really, non-answers — for yourself.