I hope it is tbh.
One thing about elections, the leader of the opposition has to get a significant proportion of media attention /a platform in mainstream media to give their vision / policies for the wider public to see and hear.
Corbyn has not had that so far as leader of opposition (admittedly he's been poor with the chances he has had so far).
The general public so far in the most will have made an opinion on him through 2 minute snippets from the news etc.
Also, if he does lose, even quite badly, at least we can move on rather than drag the in-fighting and constant battles for the next 4 years.