Something being a lepton has nothing to do with whether it's a point particle. Pontryagin duality of position/momentum (which comes from both QM and Relativity

Something being a lepton has nothing to do with whether it's a point particle. Pontryagin duality of position/momentum (which comes from both QM and Relativity, depending on your perspective) rules out the physical existence of point particles. It would require infinite momentum to have zero extent.