To me, I'd say it means you've excluded a few other successful attacks.ObsidianJones said:The first successful attack on our soil since 9/11. That means something to people.
However, in regards to your main pint you are of course right. Imagine if there was a bomb in it, and the police didn't bother to take it seriously because it looks like a joke.
There would be outcry, it'd prove forever (or at least a week) that Americans, US police, gamers were dangerously stupid, people from other nations would be scoring points of them forever. Oh, and yeah, quite possibly a bunch of people would die.
If nothing else, treating probably hoaxes seriously is good practice for when it isn't a hoax. If there's a problem, better to find out about it with an unscheduled not-exercise.
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Actually, imagine if there still wasn't a bomb in it, but police didn't take it seriously. I daresay a fair few people would (quite rightfully) be complaining.
As an aside, I'm glad I'm not a member of a bomb squad.