I was curious about the second link. The gist appears to be:

In other words, even when the people speaking loudest or most eloquently don’t intentionally discourage participation from people who are not like them... entertaining ‘politically incorrect’ or potentially harmful ideas out loud, in public (so to speak) signals people who would be impacted by said ideas that they are not welcome.

I think the idea is that rationalists are more likely to entertain potentially offensive ideas under the premise that traditional morals/boundaries/taboos may interfere or bias totally clear, unflinching rational thinking.