If I'm not mistaken there was a fish rearing station around or above the Chimneys Picnic area (which used to be a campground) and that many of the brood stock would end up in the park in the WPLP. Also, I'm not sure how long they have been stocking the WPLP in Gatlinburg, but they have put some pretty large fish in there that could conceivably work there way up into the park.
I doubt the Park Service is interested in creating a Trophy Section on one of the streams. I'm not sure any of the streams are large enough to have a section where that could be properly developed, anyway. Plus, they have so much on their plate, with so little funding that it would not be easy to pull off.
Lastly, I think having a trophy section in the park, in such a fragile environment (small streams, little food) would be an invitation to wind up getting over fished (and poached, as well)...
"Even a fish wouldn't get into trouble if he kept his mouth shut."