One very easy explanation is that they trained Sky using another voice (this is the claim and no reason to doubt it is true) wanting to replicate the stye of the voice in "Her", but would have preferred to use SJ's real voice for the PR impact that could have.
Yanking it could also easily be a pre-emptive response to avoid further PR drama.
You will obvious decide you don't believe those explanations, but to many of us they're quite plausible, in fact I'd even suggest likely.
(And none of this precludes Sam Altman and OpenAI being dodgy anyway)