[jakear]

I don't think they do need technical credibility to "prove" themselves as a fork.

If it were the case that all was well in Zion and nobody had any desire to leave Rust, then sure this would need to make a compelling argument on technical grounds. But that's miles from the truth: a large number of folks involved in Rust have wanted to leave it, and not on technical grounds. If this is the fork that can attract people who have technical chops but don't want to deal with the Rust bureaucrats, good on them. The progress made so far in splitting off while maintaining upstream compatibility seems genuine and nontrivial.