I really don't understand their policy on the Single Riders Line, but I have a hunch they'll soon drop it and just keep the SRL open constantly. Keeping people waiting in a line outside of the queue, confusing guests that are just trying to get into the normal line ("What's going on, is it closed?"), just so that the line inside of the queue doesn't go past the bottom of the stairs is absurd to say the least. There is a lot of wasted effort on the part of the employees working the front of the queue, needing to direct normal riders past the Single Rider queue. So long as there is a considerable line for the ride, the SRL should be open to anyone willing to fill an empty seat regardless of how long it gets.
My buddy and I went to get into the SRL on Saturday right when they opened it up and the girl tried to tell us we couldn't do it since we were together. He was all worried that we were doing something we weren't supposed to (clearly an amusement park amateur ), but I assured him there was nothing they could do. It was nice waiting ten minutes instead of 45 since we don't have season passes and wanted to get as much in as we could. We weren't trying to cheat the system, we just wanted to get on the ride. We were willing to ride separate from each other, and we did. I even lucked out and got to ride in row 16, which was fantastic.
Single Rider means you're willing to ride alone to fill what would be an otherwise empty seat, not that you don't know anybody else in line. Unfortunately it's not a logistical possibility, but I'd love to see more Single Rider lines. So many times I see empty seats on The Beast thinking, "Ah, but that could be me!". I remember my last trip to Universal Studios five years ago was greatly improved by the Single Rider Lines they've got.