Well that is not what defines a revolver as a double action.
A single action revolver is defined by the trigger preforming a single function and that is releasing the hammer from a cocked position. Without the hammer being cocked the trigger can do nothing.
A double action revolver is define by the trigger doing both cocking and firing with a single pull of the trigger, (hence the term double action) some double action revolvers can also be cocked manually and then can be said to be in single action mode.
All modern double action revolvers weather classified as double action or double action ONLY (unable to be placed in a single action mode) will have a swing out cylinder and when one swings out the cylinder to check for loads one should always rotate the cylinder to verify that a round isn’t still in the 5:00 (O-clock) position. I call this a redundant safety check and will only work if one always preforms this function.
And in the case of a simi auto handgun where there are single action, double action/single action and double action only, a redundant check would be checking the loading path after 1st dropping the magazine, then check of the chamber then a check of the loading path by elevating the muzzle and then looking through the action verifying that a magazine is in fact not still in the pistol.
If one is observant, which one should always be anyway, and it is a modern Center Fire DA revolver one can see cartridge case heads in the gap between the cylinder and the recoil shield. Now this isn’t a foolproof check because the cylinder chamber opposite the crane where the cylinder rotates cannot be seen, but one can get a preliminary assessment prior to a hands on cylinder swing out check that cannot be done with a cocked hammer without first de-cocking, thereby no check from the muzzle end need ever be done.
And the Statement,
is the only way to treat a firearm.