Oh my, you’re right, there’s no explicit permission to use the derivative work! It is plausibly implied by clause 1.b:
b. to translate, adapt, alter, transform, modify, or arrange the
Original Work, thereby creating derivative works (“Derivative Works”)
based upon the Original Work;
though taken literally, this would require the modifications to be distributed as patches on top of the Original Work.
This is bad.
To be sure, it insisted on it being “freely available to the public” under the BOSL license (at least), but nowhere does it say that this must be an exclusive license.
[…]
No, because you can’t distribute theorchard
crate under MIT, and by assumption,
I’m losing you somewhere…
Are you saying I can take the orchard
crate (whether with our without my own modifications to it) and distribute it under dual BOSL/MIT?
That means I’m saying “Hey, downstream recipient, you’re allowed to use this version of orchard
under MIT or BOSL as you prefer.” But we agree that’s false — they not allowed to use orchard
under MIT.