Given that the House and Senate do “make their own rules,” isn’t almost everything they do related to defining what qualifies as a majority (quorum) Consititutional? In US v Balin SCOTUS found that
… [t]he Constitution has prescribed no method of making this determination, it is within the competency of the house to prescribe any method which shall be reasonably certain to ascertain . . . the presence of a majority, and thus establishing the fact that the house is in a condition to transact business.
I won’t be shocked if today’s SCOTUS choose to hew to their faux originalist ideals (There was no videoconferencing in the 17th Century!!) and ignore precident, but this seems pretty cut-and-dried.