I'm not sure about this one.
AFAIK nobody's called it UC when the kicking team huddles near the ball, some players come out of the huddle walking toward their goal line, and others kick and cover the ball. The object's the same, the only difference here being the element of falling down as a way to have the kicking team near the ball.
Would it be unsportsmanlike for a receiver in the middle of a pass route to deliberately fall to the ground? If not to fall to the ground, how about to stop and scratch a pretended itch?