Cathay just wants factors of production, at the most efficient price. If you say that you will take an SO position, no matter how qualified you are; that is what you will be offered! If that is all they recruit in the future, it is not a bad thing. That would mean CX turned into an airline based on seniority; which should actually encourage you about your career at CX.
Think about what you would take, an SO course now, or a DEFO course in 2 years? If you wait, then any SO that joined in that 2 years is going to be a Captain before you are, and you might wish you could have gotten over any ego you may have about having 3 stripes, instead of one, for doing the same job.
Good luck!