STP
The Cathay Pacific Group had four airlines, Hong Kong Express Airways Limited (UO), AHK Air Hong Kong Limited (LD), Hong Kong Dragon Airlines Limited (KA), and Cathay Pacific Airways Limited (CX). KA pilots were not employed by CX, they were employed by KA, the same way UO pilots are employed by UO not CX. The various pilots across bases that have been let go, and the pilots made redundant were employed by CX. KA was a valued part of the group, and their employees earned the mutual respect of other employees in the group, it would however be a misrepresentation to suggest that a KA employee was a CX employee, or a UO employee is a CX employee.
The best analogy I can give you is IAG group (Air Lingus, British Airways, Iberia, Level, and Vueling), IAG closed down OpenSkies their airline based out of Paris last year due COVID. BA also made many pilots redundant due COVID. The argument you are putting forward is like saying the pilots that were out of job when Openskies closed down that have the right to work in the UK should be employed by BA because they were part of the IAG group. Not only should they be employed by BA, they should be employed before the pilots BA made redundant were rehired because they are older.