Steal after BB

[DeRef]

ASA Mens SP w/ Stealing

R1 at bat with 3-2 count. Next pitch is a ball that crosses the plate but is not in the strike zone (high). Batter begins to jog to 1B while the ball is returned to F1 who is on the pitching plate. As the BR approaches 1B, he notices that F4 and F6 are not paying attention, he touches 1B and breaks toward 2B. He reaches 2B with out a play being made.

There was a long discussion between the PU and the DC who felt that you can not steal when the P is on the pitching plate. The runner was allowed to stay on 2B.

Can anyone come up with a reason (rule citation) to return the runner to 1B?