Your logic is flawed on every level.
First point: "if guns are illegal and outlawed nobody will have them because criminals obey THOSE laws"
It has nothing to do with obeying laws. If nobody has guns, nobody can get those guns, including criminals. Very few criminals would be able to get their hands on a gun. For gun black market to appear there needs to be some source of guns. Can't have a source of guns if there is nobody to buy or steal them from.
Second point: "Then they hope nobody brings up California or Chicago"
It cannot be compared. Those states don't exist on their own, they are surrounded by other states where everyone can get guns and bring them to California/Chicago without border check. It is stupid to compare Chicago to countries with strict gun laws. Only heavily biased person pushing pro-gun agenda ignoring all logic and facts would bring it up.
In civilized country there would be 0 deaths. Attacker would have tried to beat up or attack manager with knife (there is a chance of fatality, but very small one), the hero guy would have disabled attacker until police arrived. That is what proper victory looks like.