It's regrettable that a once clinical, non-judgmental term like "mentally retarded" was reduced into pejoratives like "retard" or "f---tard" for anyone who disagrees with you.
The mentally disabled are the most conscientious and kindest people I've ever known, and I played and worked with them in school from kindergarten through the 8th grade.
To accuse someone of being "retarded" should carry all the moral weight of calling someone a paraplegic.
If you have to, call someone out for holding policies that are obviously foolish a "fool." Or call someone out for hypocrisy a "hypocrite." But using some sort of variation of "retarded" seems demeaning to all of humanity.