Anyone informing like that does not deserve business. I suspect the day will come when ordinary people will regret doing business with that store.
But if you want a 9mm in steel core, OMG! My hunting ammo in 30.06 will penetrate 3/8 plate easily. I wouldn't want to be on the receiving end of that even with a vest. I have also gone through 9 inch pine trees with the same load. Much is made of the Barrett .50's, but normal .460 Weatherby mag rounds are very near the same ballistics as far as normal shooting is concerned. The Barrett is fine looking, has better range and ballistics, but I wouldn't want to be hit with a .460 either. Arguing over a few foot lbs. is irrelevant when talking about armor piercing. I think most rifle rounds above AK or .30.30 will probably penetrate a vest. These "powerful assault" rounds are really just a little more than pistol energies.
To get their panties in a knot over a .223 in steel is ridiculous.