[Caledor]

IMHO, wizards that have any kind of restriction or special rule regarding the way they generate spell, should be excluded from having undeath. This cuts off all loremasters (with the lone exception of Mazdamundi) in addition to all the mages that already don't have it, whom i mentioned in my previous post. This because the loremaster rule states "The wizard knows all the spell of the chosen lore. The lore in question is normally given in brackets as part of the Loremaster rule." thus they cannot choose undeath. But i'm no GW so, after seeing the dispute where players want to be able to "ignore" loremaster and generate from undeath as normal, i wanted these players to be able to do so.

To Ed. To me it's the opposite instead. The item is worded in a way that is practically identical to the Magic pharagraph that all wizards have so he should gain access to undeath without worries. On the contrary, i wouldn't add undeath to the randomly generated lore of the Wizarding Hat, since the item clearly states how the lore is "chosen" (thus being one of the aforementioned restrictions).
But again, there is nothing in what i said that is even remotely official, so everything is completely open to discussion.

Edit: I forgot to mention it before, but another exception to the "loremasters that can opt for undeath in AB" is Khatep. The reason for him is that he's always the Hierophant, which forces him to chose Nehekhara anyway.