Hmm, I've been under the impression that at one point they said it'd be 100% FOSS by the time 1.0 hits, but maybe I misunderstand/misremember the details. But I remember they'd said it'd be FOSS in connection with 1.0, seems weird to do it this way instead of waiting until it's all FOSS then cut 1.0.
Make of that what you will.
A compiler promising source stability is a different commitment than the compiler’s code being ready for outside contributors. Which is also different to having ABI stability, which took until 5.0 for Swift to achieve (I think Mojo does not have ABI stability as a goal as it doesn’t have to link to OS frameworks).
If Mojo's goal was to make evolution easier, they would have a limited closed beta like what Jai does. But they're not doing that; they make the toolchain available to everyone, they just did this marketing push around releasing version 1.0 of their language. They're making it harder to make breaking changes by seeking users among the general public.
I have no idea why you started talking about outside contributors though, nobody's arguing that they should accept outside contributions. You do t have to do that. It's a completely orthogonal issue to what we're talking about, which is releasing the code under a FOSS license.
I feel like they're going to remain closed until Qualcomm is convinced they can't make any money from it being so.