I'll take that question given that I have responsibility over the directive on security management.
I think the answer is no. They wouldn't have been able to begin work. There's a standard on security screening that outlines the security screening requirements for all duties and positions in the federal government, including those of contractors. They would have had to follow those rules.
The responsibility, though, resides with the deputy head, the chain of command and the delegated authorities within a particular department, including the chief security officer, to make sure that those guidelines and those rules are followed.