Thinking about it they may also have assumed that once the forensic team went in there were no longer people remotely surveilling the shop. Hit the shop before surveillance is pulled and you risk missing someone and getting followed; which might compromise more than the existence of a heavily armed strike team. Could that team have been part of the revenge strike Nazir was planning against the US? I'd been assuming the plan was to hit something overseas; but maybe he was aiming for a domestic target for a bigger splash. If the tailor had something either critical to the team's strike, or immediately compromising for them, I could see going for a high risk attack; especially if the security timeframe you're worried about is only a handful of days. If you just need to buy enough to delay to hit your original target then the risk the government can follow up quickly enough to derail your plan seems fairly low. (Although immediate heightened general security in response to the Gettysburg shooting might be problematic even before they piece together any usable intel on the shooters) Still, a straight up smash and grab against a government team doesn't seem like a smart or winning play. Hopefully the show goes somewhere good and believable with it.