The requests for answers on Silverlight support in Win RT have been ongoing for 6 months now.
Basically either whoever MS appoints to answer doesn't even know silverlights future on Win RT (if it even has any) or MS simply doesn't want to come say 'NO it's never going to be supported we've killed our own platform'.
We all know it doesn't work now the answer everyone wants to know is WILL IT!?
Steve Jobs killed Silverlight with one statement: "There will be no plugins on the iPad... The future is HTML 5..." He is laughing in his grave with Satan.
On the other hand, it works just fine on Windows 8 and should work on Surface Pro... So if a few sites need to provide support for WinRT, they already had to cross that bridge for the competitor platforms anyway. Silverlight will be supported by MS for 10 years ending in 2021 I believe... Bing it.