That's the point of this article. It shows that both sides get very emotional over the things they take pride in. Conservatives get emotional over pride in their national identity (Don't burn the flag!) and liberals get emotional in their pride over racial/gender/sexual identity (you can't tell me what gender I am!).

I think the larger point here (and I'm not sure if the authors themselves saw it) is that regardless of alignment, when people feel attacked they get more emotional and embrace increasingly extreme views.

Perhaps this should serve as a lesson to all of us that unchecked-emotion is the root of political conflict.