Very true, but does that mean that Lazarus is still around, doomed to immortality until the Second Coming? Probably not (though I've seen that idea made into good fiction), and where there is one exception to a general rule, there can certainly be two.
Personally, I lean towards the second witness being Moses, but I would be neither surprised nor disappointed if it turns out to be Enoch instead.
My only problem with it being Moses is that the witnesses are killed, therefore whatever bodies they have at the time would have to be mortal bodies. If Moses has a body now, it is immortal. Enoch and Elijah both took their mortal bodies into the presence of God. They have not yet had their appointments with death.
Hey Buggs, where have you been lately?