Traveling or nothing!

[VaCoach]

I have seen this called many times over the years, but would like to know if the call is correct and where in the rules does it state this is a violation.

Two teammates secure a rebound at same time, neither realizing that other player holding the ball is a teammate A1 has a pivot foot established on the floor the entire play. A2 is tiring to pull ball away and he moves both feet while tiring to do so. One player has a legal pivot foot and one is moving both feet while both are in control of the ball. I have seen this called walking many times. Is that a correct call? Where in Book is it found? Why should the illegal players actions hold more weight than the legal players action?