I always interpreted that when someone make a reference to political correctness that it's a way to cover up a racist, misogynist, antiLBGT or anti-liberal comment. Pretty much what the cartoon says.
It's actually a myth, like the article says, because it's much one sided since only privilege whites think that political correctness is imposed onto them by the rest of the people they despise but somehow they feel oppressed for not (spewing) speaking their racist, misogynist, antiLBGT or anti-liberal mind. As an example: a privileged white is frustrated that he can never say the n word, thinks it's exaggerated that someone can be offended, so is frustrated to remain < politically correct > and substitute the n word for a accepted word like Africain-Americain.

I'm liberal but I think we've gone too far with PC, so I guess I'm a super snowflake cool, lol