If this person didn't have a gun you honestly believe he wouldn't have found a way to hurt someone?Ok, first, obviously, this question is stupid on it's face as "hurt someone" is somehow supposed to be as bad as "killing many people including many children"? How much of a heartless ass do you have to be to even posit that? Don't answer. Instead let's rephrase:
If this person didn't have a gun you honestly believe he wouldn't have found a way to [kill a bunch of people including lots of children]?This one is easy: "Yes, yes I do." Okay, are there really people out there who are so stupid to believe that if this person had shown up with a knife that the results would have been the same?!?
Then there are the people who believe arming the teacher(s) would fix this, which assumes 1) that the teachers would all think bringing a loaded gun into a classroom was a good idea and 2) that in such a situation having civilians with handguns shooting also would somehow make things better.
Gun advocates are simply insane/idiotic/evil/all-of-the-above.