The problem is, do they have an alternative that would be accepted by the majority of the House? Doubtful.
So are they willing to shut down the chamber rather than having McCarthy continue?
McCarthy is probably the consensus candidate, the best option for all, even as their disagreements mean that he won't be the perfect speaker for many.
It's not about trust; that's not really how the position of Speaker works at this point. It's about whether they want to do their jobs and work together or not.