Let me answer.
I am a gun owner. I concealed carry every day. As I type this I have a Glock 19 loaded with Gold Dot +Ps on my hip. I am the definition of a gun guy/nut/enthusiast. If you do not know where your gun is, you should not own that gun. If you "forget" that you have a gun on you, you should not be carrying that gun. If we follow your logic and the guy "forgot" he had left his gun in his car and one of the kids from the school found it and shot someone, the guy would be innocent. That is not how responsible gun ownership works.
The guy in the OP and the guy from the school both need to be charged with the appropriate felonies. Its because of idiots like them that I can't carry everywhere I want to. Fuck them and I hope they can never touch a gun again for the rest of their lives.
No, it's not responsible. It's also not grounds for years in prison on a felony conviction. A warning, ban from the property, revocation of carry permit, or misdemeanor conviction are appropriate reactions.
This is how the law already works in sane states (and apparently also in New York before the SAFE Act). Carrying somewhere prohibited is a felony only if it's done with ill intent or results in an injury. Otherwise it's a misdemeanor. The idea that someone can commit a felony without intent or gross criminal negligence is absurd.
You understand that politicians who dislike firearms would try to disarm you regardless of whether any of these other idiots existed, right? The rare irresponsible CPL holder isn't the reason for restrictions on carrying.