EverestUmp

When a batter hits a fair ball with one foot completely outside of batter's box, it looks like the ball is still live from my reading of 6.03(a)(1). True? Plate umpire calls batter out immediately removing the force for any runners on base, but runners can advance at their own peril? So defense gets the immediate out, but runners can take advantage if the ball is hit well? I had this happen in a game last night (I was plate umpire). Runner at 1st, batter bunts with one foot completely out of the box and on the plate. I call BR out immediately pointing at him with my fist raised but nobody notices ... the crowd is yelling louder than I am and everybody is watching the action of the ball. Defense throws BR out at 1st ... but he was already out and R1 was not forced. So batter did his job of advancing the runner to 2nd via an illegal action. I'm new to umpiring and this seems odd to me that the offense can benefit from their illegal action because the ball is still live, but that is how I read the rule. If it had been a screaming drive down the line maybe R1 gets to 3rd or home on this illegal action.