NCAA Rules Interp help

[NSABlue]

This happened to my daughters team and was looking for help with the rules interpretation.
Situation: R1 @ 2nd base and one out. Batter hits a sharp ground ball which is fielded cleanly by the 1st baseman. The Batter-runner takes only 3-4 steps toward first and stops. This forces the first baseman to either throw to 1st for the out or come towards the plate and tag the runner. She chooses the latter and R1 advances to third. When the 1st baseman comes to tag the B-R she tags her up near the shoulder. As she applies the high tag (No malicious tag, just a little high), the B-R leans back towards home plate. The B-R never moved her feet. The plate umpire calls the B-R out and leaves R1 at third. The defensive coach appeals to the Plate umpire who then confers with his partner. After the conference, the umpires return R1 to 2nd base. Is "leaning back" considered
moving back toward home plate in NCAA? I understand the rule but I disagree with this interpretation. Any NCAA blues out there that can shed a little light on this one?