Any time we encounter the argument that Trump shouldn't have nominated anyone to fill the vacant seat, I think we have to cite the Constitution as rebuttal. Article 2, Section 2 of the Constitution says the President "shall" (the word "shall" is mandatory language -- it means he must do it. If he doesn't do it, he isn't doing his job):
"... and he shall nominate, and by and with the Advice and Consent of the Senate, shall appoint Ambassadors, other public Ministers and Consuls, Judges of the supreme Court, and all other Officers of the United States, ..."
That's it. Game, set, match. By making a nomination, Trump was only doing his job. Now it's up to the Senate to approve the nomination, or to reject it. So any time you encounter someone saying (or posting) that Trump shouldn't have made a nomination, tell the person to read Article 2, Section 2 of the Constitution and then explain why they think the President should ignore the Constitution and not do his job. And then remind them that Ms. Ginsberg herself said that the President serves for four years, not three. In other words, he is still supposed to carry out the duties of his office during the fourth year of his term, and nominating Supreme Court justices to fill vacancies is one of his duties.