Bahahaha, if Starmer even had thoughts about doing such a thing, he wouldn't have gotten the job he did. He's there specifically to ensure such "socialist" ideas don't come to the forefront again (like they did with Corbyn), and if by magic he ever suddenly shifted even remotely to the left and they do, he'll just get replaced and the party purged again.
Yes, it’s an idea for an alternate reality where Labour retained some belief in equality and wealth redistribution. Sadly we live in a hellish neoliberal mirror universe where the Labour leadership salivate whenever the Davos Boys ring austerity’s bell.