On one hand, I think there's an argument to be made about this depending on how "secure" is defined, but this has too much in common with the case that promiscuous enough clothing implies consent, so I'll reject that notion outright.
And "robbery" implies force or the threat of force. If somebody has a gun to your head and tells you to give you the gun in your safe or the gun in your nightstand drawer, is there really a meaningful difference? I somebody stabs you then takes your gun while you crawl around bleeding, does are you really any more/less a victim based on where they take it from?
I don't think they're that different. I also don't think there's many (any?) cases where kids are getting their hands on gun where existing laws could/should not be used to charge the owner, as happened with this case. I'm rarely in favor of new laws when the existing ones would accomplish the same goal, were they actually being enforced consistently.
The "safe storage" laws are usually pretty worthless just on how they define "safe" on top of the actual problem with enforcement. They're not meaningful in any practical way, as anyone responsible enough that they should be allowed to own a gun already locks their shit down.
People who only lock their firearms away because they're required to are the reason shit like Nanovaults are so popular. They're a good-sounding concept, but in reality are held together with flimsy plastic internals. You can literally pry them open with a knife or housekey, or even just slam them onto the ground to pop them open.
tl;dr: Given the lax legal definition of a safe, using one doesn't necessarily add any meaningful security.
As an aside, I have safes for valuables and documents I'd like to survive a housefire...but I don't have any record of owning them. Were they stolen, I don't think it'd be easy to prove I didn't have them.