Balk question

[TwoBits]

This situation happened twice this weekend to umpires in my association (one of those umpires being me.)

OBR, R2, outs don't matter. R2 breaks for third. Pitcher has already started his delivery to the batter, but the screams of, "he's going!" causes him to halt his delivery. Balk is called immediately by all umpires on the field in each case. Pitcher steps off the back of the pitcher's plate and throws the ball wildly over the third baseman's head. R2 scored in each case.

OBR 8.05 APPROVED RULING: In cases where a pitcher balks and throws wild, either to a base or to home plate, a runner or runners may advance beyond the base to which he is entitled at his own risk.

Since the pitcher did not make the throw from the pitcher's plate and instead stepped off the back of the rubber, should the play have been killed? The pitcher did throw immediately after stepping off in each case.