Gregor Wolbring, who is an ability governance, science and technology governance, disability studies and health policy scholar at the University of Calgary in Canada, wrote an online column July 31 about "The Power of Language."
In the column, he discusses the BIAS FREE Framework (BIAS is an acronym for Building an Integrative Analytical System For Recognizing and Eliminating InEquities). He reprints a table of its concepts, which I think are relevant to the previous posting about "Tropic Thunder."
For example, with the problem of objectification, the BIAS FREE Framework asks: "Is stripping people of their intrinsic dignity and personhood presented as normal or unproblematic?" The solution: "Recognize that every human being has intrinsic dignity and human rights that are inviolable and must be protected, and conduct the activity accordingly."
IMHO, when you use the R-word, you are stripping people with intellectual disabilities of their dignity and personhood.