No Laughing At This One

[Chess Ref]

Last night in local SP action. Batter gets in the right-handed batters box. One pitch goes by, batter requests time,granted, changes over to left-handed box. Defensive team goes ballistic. manager says after a pitch no switching. This one threw me for a little loop. I haven't heard this one yet. So we discuss I say batter can. Manager protests. We then call over league UIC-who is park director and not an ump-he goes with my decision.

So after game I dig out the rulebook to see if I am missing something. The only rule I can find pertaining to switching is 7-3-D.....

Am I missing something ?