While this is literally true (anecdotally, during the peak of it in early June, I registered 106db standing still in a suburban neighborhood just outside the beltway near a large tree playing host to quite a few of them), I'm going to go out on a limb and suggest that it's not the noise that drove people to gas the bugs. More likely in my mind:

1. protecting young trees

2. a perceived need to protect brush/flowers/etc.

3. mitigating the landshrimp "ick" factor (i.e. "it's big, gross, and lands on my shirt for no reason").