The only reason I can think of is that Republicans are probably not capable of electing a new Speaker (who is not McCarthy) before the 45-day reprieve expires on government funding. The House needs to be functional in order to pass a budget.
I find it highly doubtful they will be able to fill the position at all. The only reason McCarthy has it is because he gave in to the Freedom Caucus' demands and got himself into this very position (which many predicted would happen). It's up to the GOP to lead their majority, and they can't even agree who that is amongst themselves.
What a shit show. They put their own party against doing the business of the people.
I'm secretly hoping enough Republicans get so sick of the magas that they switch sides and make Jeffries Speaker. That would be the ultimate insult, both to the magas and the GOP as a whole. Alas, I can only dream.