They're not mute, but they also aren't saying stuff like that. It would mean she remembered and understood the death scene of a ~1.5hr movie at the age of 2, and understands social norms enough to concoct a dastardly plot to monopolize that edible playdoh in the OP.
Even at 3, that's a stretch. At 4? Sure. At barely 3? No way.
As the parent of a preschooler, he would absolutely say this. He didn't have the patience to sit through such a long movie at that age, but he'd play while shows are on, and he'd definitely catch any intense emotional or musical moments.
And he could certainly plot, if a bit hamfistedly! At a little before three, he'd come up with some excuse for me to leave the room whenever he wanted to do something he wasn't supposed to ("Mommy wants you!"). If that kid realized she'd been upset by the scene, I could totally see her taking that one step further to make others upset at an opportune moment!