Within this context it’s replacing guns with water pistols, systematically and comprehensively, in the name of fighting gun violence.

On the same token, it’s replacing a water pistol emoji with a gun—in the aftermath of an armed assassination attempt on a Presidential candidate (and former President)—on a platform that regularly censors, in the name of free speech.

Performative nonsense designed to appeal to emotions instead of doing something about the implied problem. (Guns and censorship, respectively.)