Play at home

[rodneyw]

Runner on third base, when pitcher starts motion to plate
runner takes off. Batter at plate has squared to bunt, he
pulls bat back runner slides in front of him to plate and under tag. Batter did not move and no contact between catcher and batter. PU calls him safe, then FIELD Ump wants
conference they talk and then decide runner is out because batter did not move. What is your opinion also if batter does not pull bat back would that make a difference.

Thanks for your comments