Eh, why feed Reform or Conservatives any on-the-edge voters at this late an hour by making them fear a vote for Labour is a vote for more Brexit madness.
His statements are full of weasel words too, as have other party member’s statements. It’s not an insane take, just a “I don’t think we will” to avoid arming opponents with something to fearmonger with.
They need a term, and if they can change the perspective on EU membership and see polling supports rejoining (and they’ve the funds to pump into the obscene political advertising it’ll require to not get drowned out by Conservatives like before the referendum), they just might go for it in a second term.