Given how buggy I find Win8 I struggle to see how 8.1 could make things worse, especially since they didn't touch anything in desktop mode where I'm daily confronted by glitchy shit. A 'let's block Start Menu workrounds' button is insignificant.
The strong suspicion has to be another last minute hack is about to be perpetrated on 8.1 to further discourage use of desktop mode, just like they yanked the actual menu code out of 8 RTM days before release. If they can delay fixes and break Classic Start Menu/Startisback etc. for even a week, that's a couple of users that might fall in love with Metro.
Except of course users installed those work rounds because they already rejected Metro, so hardly likely to work.