Is ‘retard’ now acceptable as an insult in civil debate?

“HHB” writes: “To enlighten the social justice warriors, graduates of the Frankfurt School and all other ‘libtards’…”.
So, the “HHB” part of the “collective voice” refers to some people as “libtards”, a conflation of the words “liberal” and “retards”.
I’m surprised that The Nation’s editorial staff allow this kind of thing to be published; arrive at your own views, and consider the rest of “HHB’s” offering accordingly.
Dr Frank
Bangkok