Undead is already an indeterminate state between dead and alive so he is saying he is between alive and an indeterminate state. Hes undead.
He’s not undead. Undead in d&d has a fairly loose but set range of meaning, it isn’t an indeterminate state. It is, within that context, determinate.
He’s a former deity, jergal. This means that he has a different status, and if you look at the options you get when first talking to him as a cleric, it says something about him being steeped in divine energy.
He’s more of a demigod
I found out that he’s an avatar of Jergal the other day. So he’s correct, he’s not alive or undead, he’s a divine entity.
He’s not saying he’s between those two things, he’s saying he exists entirely outside of that paradigm.
Which he does, because Withers is >!an avatar of Jergal, the former god of death!<
