Homeland security is saying "Tricia McLaughlin, a spokesperson for the Homeland Security Department, had said that Gibson has “a lengthy rap sheet (that) includes robbery, drug possession with intent to sell, possession of a deadly weapon, malicious destruction and theft.” She did not indicate if those were arrests, charges or convictions."

So the man may have still been dangerous. People who own firearms legally are the less dangerous than those who possess them illegally. Although it's not clear what type of dangerous weapon the man had.