“Actually, I am trying to figure out the argument where Texas has any standing on what the other states do.”
Well, my answer is that if it is a federal election, then every state within the US has standing. If it were just a statewide election, with no one going to DC and voting on stuff that affects Texas, then yes, no standing for Texas.
Art III of the US Constitution....
Texas filed the suit directly in the Supreme Court. Article III of the Constitution lists a small number of categories of cases in which the Supreme Court has “original jurisdiction.” One of those categories concerns “Controversies between two or more states.” Texas’s suit is exactly that.