I think you're missing my main point: the only users who should need the OSS version would be those competing, because FSS offers the same freedoms as OSS to users who aren't competing. I don't see how this is a poison-pill, or how it's masquerading as anything malicious. I think it's pretty honest i.r.t. intent.

Re: forking FSS. Check out what Oxide is doing with CockroachDB -- there's your BUSL example.