ALL guns including handguns have to be in a safe at all times when not used.
If you add "at a licensed gun club" or "at the police station", then you are very "British".
There is a difference between prudent advice and what comes off as making demands.
Unloaded firearms, with the ammunition stored separately is about the least likely "accident waiting to happen" that I can think of.
I don't want to come off sounding like I am arguing against the use of a safe, or lock box, or other secure storage. I'm not. What I'm against is other people, who aren't me, don't know me, or my situation demanding I meet their requirements because other people, who aren't me, and aren't in my situation have done the wrong thing, in
their situation.
Living in town with your kids & teens and half the neighborhood's kids and teens rampaging through your house (mostly unsupervised) on a regular basis, is one situation.
Living miles from town, with your youngest child a staff sgt in the air force, thousands of miles away, and not even having had an adult visitor in several years is quite a different situation.
Living in town, single, in your late 50s, with the only other "people" in your house being your late mother's two cats is still another situation.
I know people in all these situations and many other different ones, as well.
Some of them have gun safes, some don't.
These people take what they believe are prudent precautions. They aren't the ones you need to worry about. The ones we need to worry about are the ones that won't listen to advice, or demands or even the law.
back on topic, there is another way to store guns long term, that absolutely protects them from rust, and that is wax. A proper application of a paste wax will seal all surfaces from contact with the air, and doesn't evaporate.
One "long term" storage I heard about was found in NY back in the 70s. A couple bought an old house to restore, and in the attic was an old trunk, which contained some Civil War era letters and the remnants of a uniform. also a rather large, and unusually heavy block of paraffin wax.
The wax block contained a pristine 1860 Colt revolver.
Maybe not the right method for your situation, but it absolutely did preserve that gun, for over a century!