We know that Buddha's Hand is always propagated vegetatively because it does not produce seeds, but I've never heard of any hybrids before. I've always assumed that the pollen is not viable and that the fingered fruit would have died out without human intervention. If the pollen is viable then it may or may not carry the 'defective' gene which produces fingered fruit. Clearly, with this hybrid the trait has not been passed on. The resulting plant may be no different from a Kumquat hybrid with some other citron variety.