At least the current response indicates that the NYPD understands the rough operational equivalence in being able to catch terrorists vs being able to catch people who switch out flags on bridges. IOW, they recognize this as a problem (even though it's unsolvable, hence the reason for security theater rather than actual measures that would prevent terrorism).

The majority of people are probably indifferent to this. But for some reason those people who wouldn't mind NYPD not wasting money on this investigation are less vocal or less influential or something compared to the pro-security-state advocates whose position is "OMG could have been terrorists!" The latter may be mostly bureaucrats in power (perhaps the reason for the overriding influence of this paradigm) worried about it for job security reasons, but the motive doesn't matter.