Reality, the clerk knew not of what he spoke (short form: BS).
I work in a LGS and I know what I know and more importantly, I know what I don't know. If I don't know the answer to a question I check with one of the other guys in the shop that has that info running around his brain pan.
Too many folks THINK they are experts and insist they know everything. We have one of those. Nothing like mis-information to mess with a customer's mind. They walk away with what they thought was gospel and spread it further when it should only be spread on a field.
Sorry for the rant, but it hit a sore point, ignorance is fixable, stupidity in the face of fact is not and with some folks that are convinced of their infallibility, they just can't be taught.