Justice Gorsuch's concurrence in Learning Resources v. Trump is something of a Godfather-esque settling of family business. He challenges and critiques all of his colleagues (save for the Chief) and brings receipts. As one would expect, his opinion draws tart responses from other justices (which could explain why it took so long for the Court to release the opinion).
Whatever one concludes about Justice Gorsuch's exchange with Justice Kagan, and whether the progressive justices implicitly adopted arguments embracing the major questions doctrine in this case, he is correct that Justices Kagan and Sotomayor have signed on to MQD-reasoning in the past, he just forgot to include one of the most salient receipts.
In 2015, both Justices Kagan and Sotomayor signed on to Chief Justice Roberts' opinion for the Court in King v. Burwell. Of note, that opinion relied upon MQD reasoning in concluding that Congress had not delegated authority to the Internal Revenue Service to determine whether tax credits would be available in federal exchanges. Here's the relevant passage:
