First, a disclaimer: I didn't write it. I believe a lawyer did.
The "violent conduct" may be vague, but the "restraining order" is not. This wording is probably strong enough to have protected Emerson. The Lautenberg law allows the disarming of a person if there is a restraining order at all. I don't believe that Emerson was ever accused of having threatened anyone, but just with having the gun.