Rep. Brian Baird (D., Wash.) digs himself in deeper:

[Baird] said a “coordinated national effort” to disrupt public meetings with shouts and demonstrations, which he said Republican leaders were “egging on,” was reminiscent of the kinds of things that drove Timothy McVeigh to bomb the Alfred P. Murrah Federal Building in Oklahoma City in 1995.
“He believed himself to be a patriot fighting against an oppressive government,” Baird said of McVeigh, whose act killed 168.
Asked for an example of violence in recent demonstrations, Baird said someone warned that Rep. Brad Miller, D-N.C., might die and that another demonstrator wielded a tombstone bearing a member of Congress’s name.
“It does violence not to the member per se, but it does violence to the process of civic discourse,” Baird said.

I would say that Baird is not a demagogue per se, but he’s demagoguing the reputations of people who disagree with him. No, wait, scratch that, he’s a demagogue.

Beyond that, yes, death threats are inexcusable and ought to be investigated. The tombstone is stupid, and showing up with a sign depicting your congressman with devil’s horns means you’re showing up with your anger already turned up to eleven. But Nazis, McVeigh, etc. killed people, and certain members of Congress are choosing not to engage with the arguments against their sweeping, untested proposals by insisting that the primary motivation of the opposition is murder.