I think the bit about the SSG uniform is more of a generalization than anything. SSG personnel have very specific and unique insignias, belts and caps which aren't easily available in the open market. Their boots are usually imported, and aren't available in Pakistan. It's a desert-camo boot and its not produced in Pakistan.
I think the terrorists probably wore the most common commando pattern pants and shirts and that's why they're being labelled as terrorists dressed as SSG. However, I'm pretty sure the army can easily identify a person wearing a "Fake" commando BDU. So lets rule out the possibility that actual SSG commandos are a part of this terrorist attack. It's not just silly, it's highly unlikely.