I am a disability support worker, and can absolutely attest that depending on the injury level and their age/muscle tone, something as dumb as pushing them sideways a bit can dump them on the floor.

Hell, the young ones do it to each other to be jerks lol. I’ve joined a stadium full of people teasing one of my clients for not wearing his seatbelt because he fell out of his chair with an epic splat after being bumped.