At some stage, they would have to get rid of the religious contestants, as on the Shabbat before the big Eurovision contest, there are rehearsals on Shabbat. Also depending on where the contest is taking place, it might actually start before Shabbat has ended there, maybe the Israeli song may be sung after Shabbat. Also with some a large variety of singers with all sorts of effects, some are always bound to be somewhat immodest, to say the least.