I’m not sure what good firearms are against a suicide bomber.
There have been several cases in Israel of armed citizens "taking out" a suicide bomber before he could detonate his bomb. No guarantees, though.
It's been done. Many years ago, in the late 1980's, in Tel Aviv a suspicious looking guy strolled into a Tel Aviv market in the middle of July and went to the epicenter of the market. A female shopper saw him coming and watched him carefully as he stood nearby. What made him suspicious? He was wearing a neck to ankle dark coat in 99 degrees of July day. When he opened his jacket to reveal the explosives wired to his entire body he held aloft the detonator and began the ALLAH-HU AK-- he wasn't able to finish before the female smoothly drew a handgun and shot him right in the head. Although western news media said the shooter was Israeli security forces, that's only true inasmuch as all Israeli citizens must undergo military training. Oddly enough, I read this in the Miami Herald and never forgot it, especially since the other media outlets changed the story. I always wondered if the writer or the editor got canned for that little slip.
You will probably take a lot of flak (pun?), but you are right.
This is why bombing is standard MO for Moslems. They aren’t dumb. Add in secrecy of smuggling in those explosives and you pretty much have maximized death toll in an instant even with armed people/security/police in the area. Firing guns takes too long, to boot - can’t kill as many as fast. Never mind the fact they love to kill themselves while performing. That REALLY helps negate guns in the area.