The preview was far further along than the 9.1 was. And last week every developer got the week off, so nothing would have been released then anyways.
Taking htat into account we have really only waited a single week for the PTR to drop if we consider actual work days. Not to mention that the announcement happened late in teh week anyways, so it isnt like we are that far behind even assuming the PTR would drop "immediately" after the announcement.
If the PTR doesnt drop this week then we can start talking about a 9.1 situation where the announcement was released to placate outrage even when the PTR was far off, but really even then its plain to see that 9.2 is further along the development cycle than 9.1 was when it was announced.