Being that they don't even know who the shooter is or what his situation is, there's absolutely NO WAY to say that gun control would help in this situation or even that he/she was suicidal. Just because he/she DID kill themselves, there are probably an incredible amount of circumstances that would cause it and not necessarily mean he/she was suicidal to begin with.
Also, why do you say that somebody like this is less likely to go out and find a gun? What proof do you have of this claim? This sort of thing and many other crimes can be caused by different reasons, including depression or other mental illnesses, therefore saying that this situation, alone, is a situation in which a shooter would be less likely (or more likely) to obtain a gun in any particular way.