Is there a double standard going on here? Surely there is. But what is worse is that the way that Tea Baggers and the Republican leaders frame the issue is that anyone who "stands up" and "protests" the Obama administration is a patriot, but anyone who does the same to a Republican is a spoiler, a low life, and a possible traitor.
When Republicans in Congress heckle the president or other legislators, they model the kind of behavior that degenerates further into the kind of violence the young heckler at the McCain rally experienced. When Republicans do not stand up for the right to express one's opinion regardless of party, they enforce a kind of group-think that can only harm freedom of speech. The Supreme Court has defended the right of citizens to engage in robust and raucous colloquy. That ruling applies not only to Tea Party protesters but to all Americans as well.