Han wrote:

We are paying the FBI to prevent terrorism, and we have monitors
exmining websites. People who openly advertise that they are crazy
(as von Brunn did on his website) should not be allowed to possess
firearms. In addition, I am afraid that airport-type controls should
be instituted at places like the Holocaust museum(s). The ubiquitous
presence of firearms permits too many crazies to go around killing
people. If you don't want to limit firearms possession, we'll all
have to live in an armed defensive camp.

He was a convicted felon, therefore just his possession of a firearm was
illegal even before he shot that security guard. But as you might have
noticed criminals don't worry much about breaking the law which is why
passing more laws making guns more illegal has little if any effect on them.

You might also note that it was airport-type security that prevented this
particular criminal from entering the museum, that's the reason the only
person he shot was a security guard at the entrance.

As for the presence of firearms permitting crazies to go around killing
people, you need to explain why a state like Vermont with extremely liberal
firearms laws (e.g. you don't even need a permit to carry a concealed
weapon) is at the bottom of the list for violent crime in the U.S.
Shouldn't all those armed folks in Vermont packing guns result in lots of
criminal use of firearms? Hey, maybe there are factors other than the
existence of firearms at work here, perhaps dealing with those other factors
is worth a try rather than looking at disarming sane, sober, law-abiding
citizens who aren't causing anyone any problems, hmmmmm?