I'd say you're being swindled.... it's the same as, "oh yeah, he won't get any bigger if you keep him in a 10gallon...bla bla bla.."
Be careful and skeptical of what people tell you, in an effort to sell you something...especially somebody who isn't physically breeding them his/herself...
Same thing goes for all of those "captive bred" niles and savanahs that dealers and pet shops are selling....geee.... I wonder who's been breeding all of these??? They all said it was a "friend" of theirs... and no, they don't have pics of the eggs/breeding/etc...
Unless this is some "new" locality, where animals are naturally smaller, which I doubt from the sounds of your predicament, I'd say he's full of horse poop... How would he know anyway? Exporters can tell the importeres whatever they hell they want to, in an effort to make a buck...
Be careful, there are a lot of shady people who misrepresent what they sell....
Take care,
bob