Thing is, I don't think there's any point in dragging the entire Labour Party into turmoil and disrepute - at a time when they could have made enormous political capital- when you don't even have a good candidate for an alternative leader.
I just don't know what the rebels are thinking. If it comes to another leadership election (and it probably will), Corbyn will walk it again. So, an enormous amount of pain for them (and the Labour party at large)- and no gain.
I am a big fan of Corbyn's- in fact, I've just joined the LP to vote for him- but I would have been swayed away from him by the right candidate.
When he was voted in, I was immensely cheered, and thought he would have several years to work on reforming the Labour party- bringing it back to basics, as it were. And that, during that time, either he'd prove himself to be a good leader, or someone else would rise up from the ranks to take over as candidate for 2020.
Thing is, even if there is a snap election, there is no one else there, is there? Sometimes you just have to stick with what you've got.