In truth, they say what they say because they are simply are afraid that if really, really think, the old accusations of being racists comes right back to them that is why. They are hiding what they really think in other words.
That is the argument from silence. If people do not tell you what they really think then one never really knows. America elected the clown currently in the White House.
Of course, considering the constant barrage of propaganda and the conspiracy of silence as regards the truth, it's no wonder that most people really have internalised the propaganda. Public schools are the most effective means of instilling the lies while people are young and at their most susceptible. The universities reinforce it three-fold. Who would ever have thought that students would be graded on their opinions, even if backed by statistics, when all else in their work is correct?