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.
Nevertheless, Shar, Jergal and Mystra intervened in the adventure. Shar maybe even most prominent, by kidnapping Shadowheart, assigning her to find the artefact, which she did, and thus, saving the party in the first place; and prepping it to defeat the dead gods.
Jergal, well he resurrects, reclasses, gets you hirelings. If that's not influencing things....
IF you're upsetting "the balance".... The Gods will find a way to reset it. The dead 3 tried it indirectly, using mortals and netherese magic. The other Gods undid it, also using mortals. Voluntary or involuntary (Shar) They will do so again if you think you can "upset the balance". Maybe it's AO themselve who is the puppeteer of this show.
So, you'll actually notice that none of them have utilized the scope of divine power to affect the Prime or its inhabitants in a direct fashion, least of all as drastically as killing a mortal outside of their domain.
Shar - Did not use any of her own power in the slightest to kidnap Shadowheart, but instructed Viconia and her church to do so, and subsequently to retrieve the artifact. Only personally messes with Shadowheart when Shadowheart intrudes on her own divine domain and defies her within it. Cannot directly mess with any Selunite or other mortals she dislikes who are outside her domain except through other mortal worshippers.
Mystra - Cannot directly mess with Prime affairs, must send her mortal pet, Elminster, to convey her wishes. Only directly interfaces with Gale when he accepts an invitation into her own domain, and doesn't even stop him from trying to claim the Karsite Weave right until the moment where he attempts to directly usurp her
Jergal - Withers is never actually confirmed to be Jergal, and if he is, then his divine portfolio has been severely reduced enough thanks to the Three that, at least in his form on the Prime, he is no longer a 'true' deity, more like a powerful lich with abilities akin to True Resurrection and some soul tampering.
I agree with the second part, the Gods will definitely try to stop you from upsetting the balance using their mortal instruments, but if that was so easy, then there would've never been a multiversal Illithid Empire which lasted for aeons in the first place, nor vast swathes of Illithid-controlled space and colonies in the present. If you get back to the Illithid strongholds and manage to unify the Illithid species, it would take a truly momentous feat to reach and stop you, and you'd stand a real chance of winning.
