As he's already said he's quitting before the next election so that's scarcely sticking your neck out.
What no-one has mentioned is the shocking performance by Lib Dems. They're traditionally strong in by-elections and it's a geographic region they've historically done well. It was only five years ago they were hitting 8,000 in a GE. To collapse to 1000 votes is an indicator that there's really no way back for the usual party of protest
Yes, I was going to mention this. I suspect the Lib Dems will be stronger in by-elections where they have historically had a bit of clout. In Oldham though, they are not a credible alternative to Labour who have the feel of a proper protest party at the moment.