He already has caused more harm than good to the Labour Party over his stance on Brexit.
He’s been a Euroskeptic since the 70’s he sees the EU as a neoliberal capitalistic endeavor which stands against everything he stands for.
Over the past 2 years now he showed no opposition to Brexit which goes against the wishes of his party members and their constituents and against the ideals of being an opposition party.
I really don’t see him changing his tune now as he showed he is incapable of letting his own ideals take the backseat to the will of the party.