Not relying to you specifically. Half-cock notches are very deep and strong. Once the half-cock is engaged, it’s almost impossible to make the hammer fall by pulling the trigger. Whether or not the trigger is being pressed, if you release the hammer before it has reached the half-cock point, it will fall and could fire a round because the cylinder hasn’t rotated yet. Hold the trigger back as you pull back the hammer, and neither the half-cock nor the full-cock (sear) notches will be engaged. If you then let the hammer go, the half-cock may or may not stop it.
Because the half-cock notches are so strong and paralyze the gun, if you try to draw and fire when you have carelessly gone only to half-cock you will be unable to fire. This gets you killed in a gunfight, and THAT is the origin of “Don’t go off half-cocked”, not that the hammer can slip.