Flashart
Not giving you something that no other DEP is given (and therefore it would be at the expense of others) is not anti-forces. Almost all of your ex-services colleagues make fine pilots, and when they have the required experience and their turn comes up they move to command like almost everyone else.
Because you cannot accept this does not mean you are being discriminated against, it just means that the system is being applied fairly and this was clear when you accepted the contract (why did you do this?). How can you expect to be given seniority on the basis of your previous employment when this doesn't happen for DEPs with their (often very relevant) previous experience with other airlines?
A system of carrying forward seniority from previous employment would be massively complex and impossible to apply fairly - so it doesn't happen. Accept it or resign, your current attitude is incompatible with flight safety.