Dragon, how can you use the term "rightful"?
No Dragon pilot has not immediate right to work for Cathay just because they are a pilot. It is a different company (even if in the same group) and as such any individual wishing to apply must prove their own worth through the proper interview process. Just ask any pilot/cabin crew from a LCC with a sister mainline carrier. They would have had to interview to make the move.
As I have said before it is not too hard for a company to declare candidates unsuitable. The cadet process is a clear indicator of this.