I share your disgust with the legal system. However, there is a difference between a "citizen" and a "taxpayer." Moreover, "standing" depends on the legal question at issue.
Another thought occurs to me, and that is that Congress should legislate that no federal monies be spent to comply with this agreement; meaning, it is important to win the Senate as well as the Presidency.
Congress? What does he care for congress? What’s congress going to do, pass a budget?