I can't speak to Earthly's choice of license (and am not familiar with BSL). But can confirm that we have no intention of changing licenses, and if we did, it would be for another OSI-approved license.
Our monetization model follows the same fundamentals as Red Hat before us: open code, strictly enforced trademark rules. "You can modify, use and redistribute the code at will. If you distribute a modified version, please call it something else."
That means I'm more likely to submit bugs and patches to Dagger, and I won't touch Earthly