And I do wonder whether he would approve of a future decision by a conservative Supreme Court majority to overrule Obergefell v. Hodges.
Firstly, I am at a loss as to what kind of fact pattern would even allow the Supreme Court to categorically reconsider Obergefell. Secondly, a Constitutional right to same-sex marriage does not require enshrining sexual orientation as a protected class, and I don't think Obergefell attempts to take it there. Kennedy's opinion describes that the Due Process protection "extends to certain personal choices central to individual dignity and autonomy" not only to the "immutable characteristics" that civil rights jurisprudence of the Warren Court often relied on.
If sexual orientation is an invented concept-and marriage itself, is an invented concept-then doesn't that mean that it's form can be changed again?
Yes, and almost certainly will. Obergefell only says that marriage (in whatever form) cannot be a right excluded to same-sex couples.
I didn't say that the Court would
categorically reconsider
Obergefell; I was posing a hypothetical, and it wouldn't be surprising if there were some case, bearing upon the issue of gay rights, that would invite renewed discussion about the issue, either before the Court or elsewhere. I was trying to discern how you frame your viewpoints on conversion therapy with those touching upon gay marriage. And it appears that you adopt what we would call an "originalist" approach to the issue.