So you think that the mayor should have just announced on TV that all non essential personnel take the day off? The same tv that terrorists watch? Are you serious? You need to understand perception and how important it is in this war against these nutcases. Have you not paid any attention at all to how Isreal stood up to the suicide bombers?
Yeah I am serious. I care less about perceptions than reality, especially those infantile perceptions of Muslim fanatic terrorists that seem to defy commen sense. If this threat is real and time-critical, better to act aggressively to thwart it while advising people of the real possibility that if they come here and use the subway they might be killed, then to say (perhaps falsely) that we'll protect you, don't be worried, we're just posting this elevated warning to protect ourselves from possible recriminations later.