I think it depends on the nature of the work. Let's just use a simple example outside of DND first, and then we'll come to a DND example.
If you had someone who was employed as a full-time translator for the Government of Canada and on the weekends they wanted to take on contract work as a translator for other departments, that is allowable as long as it's disclosed.
If we turn to National Defence, we have employees who have highly sought-after skill sets in the world of IT and security. They may have opportunities to offer that expertise to other departments or maybe to a contractor who is dealing with another department. If they want to do that on the weekend, that's fine.
However, it gets a little more complicated when the contract work is with National Defence. If it has nothing to do with their day job, if they're doing it after hours and if they disclose it, that is allowable under the current rules.