Well, it's a truism of sorts, but it's stupid. The gun grabbers need to conflate homicides with suicides to say this, that is -- they say "gun deaths" instead of "murders".
"Gun deaths" includes homicides, but also suicides and accidents.
I don't know about you, but I am more concerned about protecting someone who doesn't want to die than I am about someone who actually wants to die. Firearm suicides outnumber homicides by a ratio of about 2:1, so conflating the two completely obfuscates what is happening.
The states with the lowest homicide rates generally have high gun suicide rates, because there are many guns available. With fewer guns, cities like New York, Chicago and Washington DC have fewer gun suicides, but they have high murder rates and they have high rates of suicide from jumping in front of subway trains and jumping from bridges and high places.
Conversely, states like Alaska, Montana, and Wyoming have 0.0% suicide rates resulting from jumping in front of subway trains. (Therefore, they should outlaw subways in New York, Chicago and Washington DC. For the children!)
It's just a stupid comparison and a stupid argument.
Japan has a higher suicide rate than the US does, and effectively no private firearms. Funny term I learned in economics - substitution. Including suicide by firearm is an error because of substitution.