One too far IMO. If I have a gun secured in a safe, unloaded, and I have the key hidden somewhere else, there is nothing that suggests somebody couldn't rummage through my things to find the key and open it. Or guess the combination after many, many attempts. Point being, with appropriate effort, there exist means for someone to bypass your security without physically breaking it.
I would go with a two-tier penalty here: Improperly secured (i.e. you don't own a gun safe) Firearms Negligence in the First Degree, along with Accessory to <Whatever>. Secured, but somebody was able to easily access (i.e. you left the key somewhere they could find it, other people knew the combination, etc)? Firearms Negligence in the Second Degree, no accessory charge. Secured, but somebody broke your security (i.e. they stole your safe, drilled it, coerced you to open it under threat of violence)? No penalty. For the third scenario to apply, the theft and B&E (or coercion) would need to be reported to police prior to the weapon being used in the commission of a crime, unless you can demonstrate you had no knowledge beforehand (i.e. gun stolen from your home while you are on vacation).Charging a parent as an accessory in their child's suicide seems like a fucking horrible thing to do. The point of justice (IMO) should be to rehabilitate offenders that can be rehabilitated, and to punish (with a life or death sentence) offenders that are beyond rehabilitation. There is no amount of prison time that will be more rehabilitative than a parent knowing they are personally responsible for their child's suicide, and to do so would be an unnecessary burden on the State that now has to pay for their living expenses. I would accept a felony charge that carries no penalty beyond the consequential loss of 2nd Amendment rights.