They were best friends in real life. In the 1930s one winter evening in manhattan they were walking along on the sidewalk while debating politics. The argument became so heated that they came to blows. They were rolling around on the snowy sidewalk trying to beat each others brains in when they came to the realization how ridiculous the both of them were acting. They treasured their friendship way more than politics and politicians, so they made a vow to never discuss politics in each others presence ever again in order to preserve their friendship.
Some who inhabit FreeRepublic would consider Mr. Stewart weak for putting friendship above politics