None of the rifles you linked to are assault rifles
I guess it's a good thing I didn't claim they were (I was joking in my OP)
and the definition of what an assault rifle is is most definitely settled.
Among the military and gun enthusiasts, perhaps. Perhaps even by legal standards. Settled among the general population? Not so much. If you care to look at how some online dictionaries define "assault rifle", take a look hereand here and here.
The reality is this: if I were to walk down the street with my AR-15 slung over my shoulder, a good chunk of onlookers will think "that's an assault rifle" (even here in Texas!).
This vendor has absolutely no idea of what an assault rifle is
I seriously doubt that. BTW, it's not just Grab a Gun calling these weapons assault rifles. There are many vendors doing so.
or is attempting to capitalize on idiots who think they're buying a rifle capable of select fire.
No, they're capitalizing on people who think that a *semi auto* rifle IS an assault rifle if it looks scary enough - and look...even the dictionary says so!