Just being there and traveling the exact same way, here is my perception of what happened.
All vehicles were going South on 2. The motorcycles were turning left into HillBilly's. There is no signage worth a darn to tell you that this place is on the left. It's almost a blind find, it pops up very quickly when coming down WV2. I believe the bikes were hard on the brakes once they had HillBilly's in sight, which is when you are pretty much on top of it!. Whether enough brake lighting etc played a part? pickup truck driver not reacting fast enough? who knows?, but the pickup rammed them from behind, at least what I perceive from this.
I had HB's on my GPS and I was still hard on the brakes to make the left into the entrance, which there is 2, the most Northern for me was easily surpassed. Shrubs and trees shelter the opening/entrance and it comes up quickly.
Bad deal anyway you look at it, and my heart goes out to those and family's involved. Very sad