 Neutrinoless quadrupole beta decay would violate lepton number in 4 units, as opposed to a lepton number breaking of two units in the case of neutrinoless double beta decay.Therefore there is no 'black-box theorem' and neutrinos could be Dirac particles while allowing these type of processes.In particular, if neutrinoless quadrupole beta decay is found before neutrinoless double beta decay then the expectation is that neutrinos will be Dirac particles.