I don't know the legal ramifications to companies when it comes to 'misprints', though, in this instant it was thousands of electrons being terribly inconvenienced.
I've ran into situations both online and in stores. Some honor it, some simply won't, but I'm the same as you, I won't support stores or businesses that can't remove their head from their third point.
I've bought a few cases of .45 from them a few months back, no problem but I suppose I'll be looking for a new ammo supplier.
I've had friends recommend usaammo.com, not a huge caliber selection but it has the basics, 5.56, 7.62, .45, 9, ect.
"You can smoke in your ghillie suit if you want, but I'm not peeing on you when you BBQ yourself." Remark over heard at US Army Sniper School 05-05