"Running Balk" ???

[AZBlue]

During a tournament this weekend, had the following:

R1 and R2, pitcher in the Set position extends leg and turns as if to pick off R2 who is leading off. R2 goes and pitcher starts running him down. Pitcher stepped forward off the rubber after feinting the throw to 2nd.

I am not sure if this was a legal move, but it looked really suspicious. Is the pitcher required to properly disengage in this situation prior to running down the baserunner?

Any help would be appreciated!

Thanks,

Jim