Preparing for After Shabbos

I attended a bar mitzvah away from home over shabbos in a hall with waiters who were obviously not-so-froom bochurim. It seems the hall has a rule that after the event the place has to be left spotless. But if the hall will not be being used again until after shabbos then surely it can't be correct to make these bochurim "prepare" the hall for after shabbos, and also clear away garbage which is seemingly muktzeh in this circumstance..... Also, should I not eat by such events so as not to be party to this if it is a problem?? Thank you

Shalom!

Thank you for your question.

You are correct that if the hall will not be used again on Shabbos then clean up should not be done. This is the ban on "Hachana" - preparing for after Shabbos.

Nevertheless, it is possible that the bochrim/caterer received rabbinic sanction and are relying on a number of leniencies to allow the cleanup of the hall even under such circumstances.

For example, cleaning away garbage is permitted for a variety of reasons, including the "graf shel re'i" dispensation which allows clearing the room of repulsive content even if it is otherwise muktza.

In any event, for a number of reasons, there is no requirement for you to avoid such events as long as they are kosher and shomer shabbos in every other way.