There are already half a million people in the U.S. with “top secret” clearance. Seems to me it will be hard to keep any secrets at all...
Just because you need clearance for your area doesn't mean all of TS info is at your fingertips. It doesn't work that way.
It's all compartmentalized and "need to know" is very real. So, while you might be working on some TS engineering marvel as a contractor, there is absolutely zero need for you to know troop movements in Afghan. And you wouldn't have access to that info.