You are exactly right. It is schizophrenic to complain about the cultural degradation in America and, in the next breath, talk about how great we are. The fact is, we are far less great than we used to be, precisely because of the abortion on demand, rampant promiscuity, and near pornographic popular culture that Buchanan writes about.
Schizophrenic or more precisely neurotic. There is a great story The Picture of Dorian Gray, a must read for some :)
Piffle. This is precisely the argument used by leftists to denegrate the Founders of the Republic (they stole the land from the natives and some of them owned slaves; therefore, they were no-good Dead White Males).