Should It Be Against the Law for "Perceived" Threats Against Federal Officials?

I think there are going to be constitutional problems with this idea:

Rep. Robert Brady (D-Pa.) reportedly plans to introduce legislation that would make it a federal crime to use language or symbols that could be perceived as threatening or inciting violence against a federal official or member of Congress.

Brady told CNN that he wants federal lawmakers and officials to have the same protections against threat currently provided to the president. His call comes one day after Rep. Gabrielle Giffords (D-Ariz.) was shot, along with 19 other people, at a public event in Tucson. A suspect is currently in custody.

"The president is a federal official," Brady told CNN in a telephone interview. "You can't do it to him; you should not be able to do it to a congressman, senator or federal judge."

The problem is the word "perceived". Right now Democrats "perceive" the Tea Party to be a threat, so should they be banned or be arrested for participating in rallies that some Democrat finds threatening?  This kind of law simply gives too much leeway for misconduct on the part of officials (was that threatening too??).

The constitution gives the right of free speech, and that includes the right to be critical of the government or its officials.  A government that's out-of-control bans all criticism that it perceives as threatening.

And no amount of new laws or regulations will stop crazy people from doing crazy things.  That's still going to happen and violent outbursts from crazy people shouldn't be used to stifle criticism from the not crazy people.