Using a safe and hiding the key PROPERLY is part of gun safety.

His dad was/is an irresponsible gun owner.

Just having a safe doesn’t make someone a good/safe gun owner just like only following the speed limit in a car doesn’t make someone a good/safe driver.

I can follow the speed limit and be swerving all across the highway. Do you see how a statement like “use a safe” doesn’t just mean to only use a safe and not follow other safety protocols like hiding the key?

Let me know if you have any other questions. Hope that helps.