I don't think he pretended it was the only legitimate response - rather in the circumstances he felt it was the best one. I think it's easy to forget how quickly the party could have collapsed during that time if there wasn't someone willing to demonstrate that the members weren't being ignored.
The interim leadership rolled over for the Conservatives in the summer after the 2010 General election, giving them carte-blanche to define why the GFC happened (Labour overspent), and that harsh austerity was the way to reduce the deficit. No one made an alternative case and it set the tone for the next five years. The same thing was happening again, as if they'd learnt no lessons from five years earlier.