as I understand, it's more than just hike-a-bike. from what I've heard, it came from walkers, not bikers. lots of downed timber and overgrowth. I've heard there's more than one, but they're more or less the same.
from how I've heard it described, it would actually achieve a rating on this scale.
Sub-Alpinism - The Brush and Bushwhack Rating System (alpenglow.org)
I have also heard that the USFS has considered an official connector but wants to see a history of better trail maintenance on the rest of the official bent creek trails before moving forward with anything. if there was an official, rideable connector between the gravel roads, it would be one I would use regularly. it would be a lot quicker for me to get from where I live onto the trails than to have to drive sardis and brevard rd to get around to the main entrance.
There are now short sections of painted bike lanes crossing over I-26 through the interchange. it also looks like there's enough room for these lanes to be extended well north, at least to 240. you can also cut through parking lots for a pretty good chunk of the busiest part, near the outlet mall. you can also chat with folks at motion makers and carolina fatz about their preferred ways to get to bent creek.