I gather the folks who believe that the same-sex marriage right existed back when it was shocking also believe that there are other rights that presently exist in the Constitution, currently unrecognized, that are as shocking to us today as same-sex marriage would have seemed in the 1700s or 1800s.
Where on earth does he gather that from? It doesn't follow.

Does he believe that womens voting and slavery being immoral would have been "shocking" back in the day? If so then he has the same "problem" he's babbling about here.