Hello and thank you for entrusting me to assist you. My name is ***** ***** I will do everything I can to answer your question.
Certainly this is "discrimination" in the sense that you were treated differently for an arbitration/unfair reason. However, discrimination only becomes actionable under the law when an employer's motivation is a legally protected trait (i.e. race, religion, gender, ethnicity, sexual orientation, disability) in which case it then becomes a civil rights issue. It is this motivation that gives rise to a claim under the law.
If you have reason to believe that your employer had such a motivation in denying you the incentive, then you may have a claim. Your first step in that case would be to file a complaint with the EEOC. But otherwise, while what your employer has done is unfair and "discriminatory" in the ordinary sense of that word, it is not actionable under any legal theory, and your sole recourse is to attempt to reason with your employer or leave for alternative employment where you are treated more fairly.
I hope that you find this information helpful. Please do not hesitate to let me know if you have any questions or concerns regarding the above and I will be more than happy to assist you further.
If you do not require any further assistance, please be so kind as to provide a positive rating of my service so that I may receive credit for assisting you. Very best wishes moving forward.