I really hope you are right and he does.
The problem is, lots of Labour supporters seem to have been relying on Farage's support of Trump to be his Achilles heel. At best, Mandleson being mixed up in the whole thing negates that. Labour can't criticise Farage's oiling up to Trump without it becoming about Mandy. And Farage isn't actually implicated directly with Epstein whereas Mandy is. So this whole thing is much worse for Labour than Reform.
Plus, the republicans very successfully leveraged suspicion about Clinton/Epstein and even managed to smear Harris by association/the democrats failure to investigate etc. They did all that at a time when there was loads of information about Trump. It didn't lessen QAnon or even more normal people's support for Trump 2nd time around.
All the awful things we know about Reform/some of the dodgy/racist characters in the party. They don't have someone who associated with an international child sex trafficker (that we know). I can't see how Labour can criticise Reform candidates in the election without it coming back on them.