OW states that Ruby members have access to "Business Class priority check-in," so if BA wants to play rogue by degrading the benefit (by sending pax to WTP check-in) or denying it altogether, I hope OW comes down with some sort of enforcement.

The simple solution is to adjust the staffing ratio between priority and non-priority counters/areas, e.g., in the MLA photo above, BA should reallocate counter 26 for J so that it has two J counters and one Y counter.