[MT 73]

Originally Posted by bob jenkins

If the batter has time to get out of the way, he must do so. Moving into a spot that is still (or becomes) in the way is INT.

I'm not sure the rules reference above is the correct one -- it applies during an "immediate" play by the catcher -- (usually) either on a squeeze / steal of home, or a pick-off attempt. It exempts the batter from INT if he stays still (other than completing his normal swing). Once the ball gets away, though, a different rule applies. I don't have time to go cite it for you.

Thanks.
No reference needed.