> I am somewhat concerned about the volatility.
Not just volatility but also flip-flopping. Rust was explicitly a contender when they decided to go with Swift 18 months ago, and they've already done a 180 on it despite the language being more or less the same as it was.
they tried swift, it didn't work, and they figured rust was the best remaining option. that's not "flip-flopping" (by which I assume you mean random indecisiveness that leads to them changing their mind for no reason)
I guess they bet on Swift being more than Apple's blessed way of writing UI software.
It's not that they are loving Rust, but they realized going all-in on Swift means becoming sharecroppers on massa Tim Apple's plantation.
They made a very pragmatic and sensible decision after reviewing Swift that it wouldn't be suitable for their purposes, so they shifted to the next best alternative. I think they reasoned it very well and made a great decision.