Coach physically assists

[SC Ump]

NFHS:

R1 on 2B with no outs. B2 hits to left field. R1 rounds 3B as coach is giving "stop" signal. B2 sees the stop signal, attempts to stop but cannot when she runs into the coach. After running into the coach, she quickly returns back to 3B as the ball is casually thrown from F7 to F6, i.e. there is not a close play at 3B.

SIT1: Coach was in the coach's box, giving stop signal by holding his hands straight over his head and runner hits him.
SIT2: Coach was several feet up the line toward home, giving stop signal by holding his hands straight over his head and runner hits him.
SIT3: Coach was in the coach's box, giving stop signal by holding one hand straight in front of him and contact is with runners arm.
SIT4: Coach was several feet up the line toward home, giving stop signal by holding one hand straight in front of him and contact is with runners arm.

I believe it is "physical assistance" in all situations but others have told me they feel differently. What say y'all?