This is an employment discrimination question, not an immigration question.
This is general information only. It is not intended as a substitute for legal advice, and does not create an attorney-client relationship. For legal advice specific to your circumstances, you must consult an attorney in a confidential setting, not in an online forum.
You need to pose your question to an attorney who specializes in labor/employment law.
The information contained in this answer is provided for informational purposes only, and should not be construed as legal advice on any subject matter. No recipients of content from this answer, clients or otherwise, should act or refrain from acting on the basis of any content included in the answer without seeking the appropriate legal or other professional advice on the particular facts and circumstances at issue from a licensed attorney. Provision of information on this website does not create an attorney-client relationship between you and The Law Offices of Grinberg & Segal, P.L.L.C., nor is it intended to do so.
This question is way outside the scope of this forum. First of all, it may or may not be discrimination. Ability to travel to certain countries because of US citizenship could very well be a legitimate requirement for this job. Second, you are probably represented by a union and need to use them as a tool to resolution. Third, this is a class-action type issue and cannot properly be handled within Avvo.