Look back rule on a walk

[Dakota]

ASA rules, fast pitch game.

R1 on 3B. R1 leads off on the pitch. B2 walks. F2 returns the ball to F1 as BR2 makes her way to 1B. R1 stands and watches BR2 walk to 1B, making no move either back to 3B or to home.

The umpire rules dead ball, R1 out on a look back violation.

Correct or incorrect? Why?

Discussion on-going over on another board. I am fishing for opinions here, too.