seems to me like UAL ALPA is cheating on one of their UAX groups that they already entered an agreement with.

from my MEC's website:

Recently, the United Airlines MEC changed the jumpseat priority codes for the UAX carriers. United's MEC attempted to secure priority jumpseat rights on United Express flight numbers behind those pilots jumpseating on their own company aircraft. They were unsuccessful with exception to Trans States who already had these provisions in place. This resulted in United MEC offering reciprocal jumpseat priority to Trans States pilots. The jumpseat priority changed as follows: On a United Mainline flights - UAL pilots have priority followed by TSA pilots as K1, followed by Skywest, Chautauqua, and Shuttle America pilots as K2, followed by Mesa pilots as an L priority which included all other offline pilots groups.