All you could do is to file a complaint with the National Labor Relations Board (NLRB - www.nlrb.gov) that you are qualified for a job that has been specifically targeted for someone who is 'younger'. They will investigate the charge, and if they find it has merit they can sanction the company placing the ad. I don't think Facebook is at risk here for facilitating but that is for a lawyer (of which I am not one) to decide.