Union protesters outside the Wisconsin capitol mob Glenn Grothman, a Republican state senator, and follow him, screaming, as he tries to get into the capitol building. Eventually they pin him into a dead end and won’t let him leave. A Democratic legislator among the protesters eventually intervenes, but even then it takes him several minutes to calm the crowd enough to allow Grothman to leave.
Watch as much of that video as you can stand. Then contrast that with the incident outside the US Capitol that got the media so exercised. In that case, Democratic representatives chose to enter the capitol building through the protesters (they could have more easily taken an underground subway from their offices). The protesters allowed them to pass without any appreciable delay, and do not follow them. The protesters certainly do not pin them into a corner where they need rescue.
Can you imagine the media reaction had the Tea Party protesters done anything remotely like what these union thugs did here?