Your linked article says white phosphorous is a conventional weapon and isn’t banned or outlawed. War sucks, but this isn’t really a good argument for such an outrageous thought. Isn’t it easier to think war alone is enough to trigger PTSD? People suffer from PTSD from events significantly less traumatic events than war regularly.

Should this person just tell their mother over a phone conversation and hope that it spreads via word of mouth instead? What’s the alternative here?