It's a pretty compelling case, Daisy might be the representation of the Shadow Magic and not the tadpole itself. As you know, there is another data mined voice file that indicates that the tadpole and the shadow weave are oppositional forces and that the tadpole has the power interfere with the influence of Shar.
In third edition, anyone who discovered the shadow weave would suffer a -2 wisdom loss. This debuff would remain until the character completed a task for Shar's church. PCs could decide to work with the Shar's church or just take the L. (but that was usually a bad choice -- the weave was so corrupting that it never made sense to avoid Shar)
Which means two things:
1. like with the regular weave, it's possible to use the shadow weave without Shar's approval and
2. Shar regulates the use of the shadow weave more closely than does Mystra.
So the dead three might have planned to use the shadow-weave modified tadpoles to create true souls. The infection allows psychic powers to develop, allows the victim to be controlled but stops full transformation. The question then becomes: are the dead three using the shadow weave with Shar's permission or not? Again, the voice file suggests that the relationship may be antagonistic.
So perhaps Shar sees an opportunity with with those in the crashed nautaloid -- perhaps she can seduce the tadpoled characters to serve her will and not the will of the dead three.
But, if this is Shar's goal she will run into a problem -- Sharess has stolen the portfolio of seduction from Shar. And just like Shar monitors any use of the shadow weave, Sharess has the ability detect the use of seduction. Sharess might end up playing a role in the story since Larian has decided to base so much of the story on a "evil is seductive" theme and Sharess wants seduction to be used for good and pleasurable ends.