Sorry for the inconvenience. This is a bug. The unused usings should not be gray if the option for "Show warning for unused usings" is disabled. We already fixed that in our codebase and the fix will be included in our next internal build.
If you have any other problems or suggestions, please don't hesitate to contact us again.
the Telerik team
Do you want to have your say when we set our development plans?
Do you want to know when a feature you care about is added or when a bug fixed?
Telerik Public Issue Tracking
system and vote to affect the priority of the items