Orin, Gortash and Ketheric still had to deal with Orpheus and the artefact. A thing which does not needs to bother Tav. But Jergal, Mystra and other Gods. Shar, for example, who must feel a bit offended, are unlikely to let you do your thing.
Imagine, Jergal struck your name from the archives during the adventure, but could then just as easily undo that, and boom. You're dead.
I'm pretty sure that straight-up eliminating mortal, material creatures, even extremely powerful ones, is a pretty big no-no in the divine playbook with different explanations as to why in any given setting or campaign, otherwise you'd just get entire races, civilizations and power-hungry beings simply getting deleted non-stop perpetually and eventually a second Divine War as they run out of minions to slay and confront each other openly.
In some settings, deities don't do that becase Ao will bitchslap them if they do. In others, they simply don't have the ability to exert such direct influence outside of their own domain, especially into the Prime Material. In yet other settings, there is a treaty between most Deities to keep their hands off Prime affairs, sort of like the divine version of mutually assured destruction, as to not get into an apocalyptic divine war.
Neither Jergal or Shar should be able to touch you while outside their personal domains, only send their followers to do so. And if you can escape into Illithid-space, then their followers shouldn't be able to do much about it either, or else the Illithids would've been destroyed long ago.
