Sounds like the senior employee is penalized for living at a hub.
This line of argument again?... Move to a spoke, and let me know what you think about all the flight opportunities you have.
Regardless, if the "thru" priority is retained, even in a DOH system you'd still be penalized, since transiting nonrevs would still have a higher priority.
Personally, I see the opposition to FCFS as signs of an entitlement mentality gone bad.
Seniority should
only be used within a workgroup, i.e determining who gets which days off, which shift, first shot at picking vacation, or bumping rights into another station during RIF/Transfer.
It shouldn't be used to decide who gets on a flight, the desk or locker closest to the door/window, the newer chair or PC, the larger slice of pizza in the cafeteria, the stall with more toilet paper, or a better parking space in the employee parking lot. Especially when it's something that transcends workgroups.
I'm the fourth or fifth most senior person in a group of about 20. I certainly don't expect to exercise my seniority when it comes to seating arrangements in a meeting, which office I'm assigned to, or where my parking space is, but that's the French mentality of liberté, égalité, & fraternité...