The wording could have been better (and the whole private beta thing as well).
For what it's worth, the protocol and data model is open and designed for redistribution [1], and the event stream of messages is freely available without login [2]. It's quite similar to Secure Scuttlebutt (which has the most beautiful protocol guide itself [3]) including the disadvantages that come with radical publication – for example described in this 2018 pre-LLM Facebook v. Cambridge Analytica-era comment [4].
[1] https://atproto.com/specs/data-model