The article talks about how it could be concerns over possible changes in gun ownership laws (because one must, simply must, have a semiautomatic assault rifle with 1000 rounds of ammo).
But I hear a bit of a nasty undercurrent, in the sentiments expressed by purchasers, that sounds like either:
"I have to be able to defend myself against the socialist jack-booted thugs that will be sent after me if the liberals win."
-or-
"I'm arming myself for when we real patriots decide we've have to take back our country."
Scary.