The Associated Press: Jewish school may forfeit basketball playoffs over Sabbath game
Talkback
Title:Christian Sabbath Observed, But Not Jewish Sabbath
Name:Zusya
City: Los AngelesState: CA
The sponsors are already observing the Christian Sabbath:

from http://sportsillustrated.cnn.com/2008/more/02/27/sabbath.colorado.ap/

"Senate President Peter Groff, D-Denver, said the CHSAA`s decision was ironic because it has a rule barring games from being played on Sunday for religious reasons."

If the organizers are making accomodations for one religion - Christianity - they must make accomodations for all religions. Major league sports and arena concerts regularly reschedule events for a different day; a high school basketball tournament can as well.