“If you use a gun, that will just escalate the violence” presupposes two things. (At least two things.)
One, it presupposes that using the gun is not effective, or that you’ll use it in an ineffective way. Because if the gun were used effectively, the violence would not ‘escalate’ when you used the gun. The violence would stop.
Two (and far more interesting on the think-it-through side of things), it assumes that you are using the gun in an unnecessary way and that your life isn’t really at risk. Because if you were using the gun appropriately, you would be using it only to save your own life or the life of another innocent person — not to threaten or bluster or make a point, but simply to survive.
There is no escalation point past “an innocent person is going to die, right here and right now.” Everything from that point on is either acting on exactly the same level, or a de-escalation.