It's not an airsoft issue, it's a public safety issue. If you ran down the street all Yosemite Sam like with any kind of dangerous device, I'd expect them to be confiscated. You lose the rights to possession by being a jackass.
I'd consider yourself lucky you got away without charges and move on to a different hobby. Supersoakers are all the rage this year.
Edit: You weren't shooting at people off the balcony were you? If so, you should be supremely grateful you aren't typing this from a cell.
Before the internet, the village idiot would stay in his own village.