I'm delighted to report (as Adam Liptak wrote in today's New York Times) that the ACLU will be representing the NRA in this important First Amendment case, and that the ACLU's Legal Director David Cole—an experienced Supreme Court advocate—is (the Times notes) planning on arguing.
The issue in the case is whether New York financial regulatory authorities coerced banks and insurance companies to cut off ties with the NRA and thus violated the First Amendment. As the petition argued,
The Second Circuit's opinion below [rejecting the First Amendment claim] gives state officials free rein to financially blacklist their political opponents—from gun-rights groups to abortion-rights groups to environmentalist groups and beyond.