I think people are reading too much into this. UA is trying to reduce the 5 lines to 2, more like AA, which simply has 2 lines (Elite and non-Elite). CK pre-boards, then first group is J, followed by EXP, then PP/Plat, then Gold. While people line up only those in J tend to line up first. EXP may hang out near the beginning of the roped off area, so they can proceed once EXP is called.

My only complaint with AA is sometimes they don't allow enough time for EXP to board, many times they call EXP, the a few seconds later - the other elites. Also - I think EXP should be in Group 1 and board with J. If an EXP is not in J (which is usually the case these days), then there is no interference with loading the overhead.

Would be better if EXP boarded before J, then if in J they have priority over other J, and if in Y, they can be putting luggage in overhead while rest of J boards.

I think this is what UA is trying to do. An 1K in UA F gets priority over a non-1K in F, and 1K's not in F (in Y), aren't interfering with overhead load. I think this speeds up the process.