The response was that that he considered himself very open minded, getting along with people across the political spectrum, but that that position was so obviously beyond the bounds of reasonable discourse
Unfortunately, Freidman picked apartheid. He could just as well have picked Citizens United, the 2nd amendment, opposition to racial quotas, and the desire to enforce immigration laws. My guess is that these would equally be held to be "beyond the bounds or reasonable discourse".
Years ago, I dated a woman in a graduate english department who would wear a Politically Incorrect button. She was basically a progressive, but unlike much of her department, not explicitly Marxist, and therefore "politically incorrect". Going beyond the progressive consensus to the right isn't politically incorrect, it's beyond the pale. Going beyond it to the left is being "principled" but "too extreme".
The range of "reasonable discourse" is generally held as the people who share the same unquestioned premises. Being consistent in them means being extreme, but rejecting them is " beyond the bounds of reasonable discourse".
He could just as well have picked Citizens United, the 2nd amendment, opposition to racial quotas, and the desire to enforce immigration laws. My guess is that these would equally be held to be "beyond the bounds or reasonable discourse".
Racial quotas are unconstitutional by a 2003 Supreme Court decision. That decision matches legal opinion. I don't think you'll find a hard time finding academics who support conservative interpretations of the 2nd amendment. I also don't think you'll have trouble finding academics who support Citizens Unite...
Related: Heuristics for Evaluating the Soundness of the Academic Mainstream, Admitting to Bias, The Ideological Turing Test