They probably have an exceptional growing set-up (soil, lots of TLC). The height you quote is typical here (Temecula, CA). Maybe to 6 ft. I'm skeptical that Tilden's plants are genetically unusual.

I sometimes think that the stalk length is programmed. I have a specimen that I bought at Sta Barb Bot Garden about 12 years ago that had about an emerging 7 foot stalk in the gallon pot. For about 6 years it produced 10' stalks that stood way out from the rest. Then, mysteriously it withered up and croaked. Luckily I vegetatively propagated the plant and so I still have an apiana that shoots up giant foot stalks although dimensionally, it's a rather small plant like the original specimen. Bottom line, it sure couldn't hurt to request some seed and see what the plant does for you.
Lucky for me I busted a guy who (mis)took this plant from my pile at the sale, giving him the wild sage look as I mentioned the plant was (re)moved somehow or other from my collection...otherwise i'd have no story to tell. Moral of the story; hold on to your salvias like they're artwork.