For contemporary relevance, all responses are from 2000 onward. Sample sizes by race are 7,751 for whites, 1,445 for blacks, 535 for Hispanics, and 297 for Asians:
Free speech is a white thing. Whether the speaker in question is 'far right'--as in the case of an avowed racist--or 'far left'--as in the case of a communist--whites are more open to discussion of controversial topics than non-whites are. Hispanics are especially hostile towards freedom of expression.
Not only does multiculturalism make members of all races and cultures hunker down more than they otherwise would if their societies were homogeneous, the specific kind of diversification we're suffering from is accelerating this process even more than heterogeneity in general would. As the white population declines, free speech will decline along with it.
The more diversity we take on, the less liberty and equality we will enjoy. These things are mutually exclusive.
GSS variables used: RACECEN1(1,2,4-10,15-16), SPKRAC, SPKHOMO, SPKCOM, SPKATH, SPKMIL, YEAR(2000-2014)