I agree that the pro-goblin/pro-Absolute route is missing some ingredients that could provide exposition and enticements.
It is certainly not the "easy route" for the "lazy evil" character, even if the big battle isn't difficult for a given party. Even playing a very evil character, it's hard to RP going this route.
We are clearly meant to think that Halsin is the most likely source of a cure, (or maybe the Gith Creche, if we aren't too alarmed by the possible meaning of the term "Purification?") It's hard to imagine why a reasonably intelligent evil main character would not just con his way to help from Halsin, and also steal or murder in the Grove as needed, and move on?
The Absolute Cultists are well-written, but in a way that should make only the most foolish of main characters say, "Sure, I am definitely on board with these loonies!"
The player needs to be confronted with more *temptation* to join as they make their journey. As written, the Absolute Cultists just come off as amusingly nutty zealots, and the player is not exposed to anything that should sway them to agree.
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I think the problem is that there are no NPCs along the way who understand the Party's actual tadpole situation, and who will make the case that keeping the tadpoles, and joining the cause of the Absolute, will be beneficial in some lasting way to the Party.
The cultists are oblivious to the existence of the tadpoles, so it's hard to buy what they are selling: We know they don't understand what is happening to them.
Ethel doesn't share much, and if anything, she further makes the case that it's not going to end well.
The Absolute needs for a Tempter/Temptress NPC to appear to the player who:
A. Demonstrates understanding of the truth of the party's tadpole situation, and
B. Will try to convince the main character that they will be *permanently* be granted special power, and will not just become a Mind Flayer, or just one of many raving zealots, like the cultists and the True Soul we meet before reaching Minthara and Ragzlin in the Goblin Camp.
Minthara's dialogue writing doesn't help here, because it is never made clear that she's any more than an overly devout cleric with telepathy. By the time we meet her, we should already have some more compelling enticement to join.
We could possibly be "playing along" with Minthara's zeal (since we haven't seen anything that should make us feel similarly worshipful to this mysterious new God/Goddess.)
Astarion is the only party member who really *should* like the tadpole, and even he expresses anxiety about the good times ending abruptly with his sprouting tentacles. His dialogue on these subjects is excellent.
