The 'Netherese' element of the Netherese-infused Tadpole is a completely homebrewed Larian invention, so a DM could easily classify it as a 'magical disease, curse, or a similar effect', with emphasis on the 'similar effect' part if all else fails. As for 'both' though, I'm not sure what the tadpole has to do with Reincarnate, unless you are unfamiliar with the spell description - Reincarnate only requires that you die and then it summons your soul itself and implants it in a brand new, magically created body, with the state of your old corpse and all effects on it being completely irrelevant.
Okay, so continuing the role as "Advocatus Diaboli", what exactly is "the state of the old corpse.
Could you kill horned Wyll and resurrect him without horns ? Or is that part of his state ? Could the embedded and netherese magic encased worm be part of the state ?
Omeluum says that the lesions in the brain caused by the worm may be lethal also, and removing it would need special care. So if you resurrect it and the brain is fatally damaged, then that would probably not help.
