Emojis are supposed to represent a specific meaning, though the visual representation can of course change across platforms. Any gun would be an appropriate rep

Emojis are supposed to represent a specific meaning, though the visual representation can of course change across platforms. Any gun would be an appropriate representation, but a toy gun is not as it occupies a separate semantic space. Your own source seems to exemplify why a toy gun doesn't fit. It specifies "pistol" or alternatively a handgun or revolver. If someone wrote "the man walked in holding a pistol/revolver/handgun in his right hand" you would justifiably be surprised if the writer later explained that it was a bright green toy gun. They're different things. Imagine if an IME decided to substitute the GLOWING STAR emoji with SUN WITH FACE. They would not be following the guidelines as the sun and stars are semantically separate concepts, even if technically the sun is a star.