But if you want to convince me, list at least one Character that is sugesting you Halsin as your best option for removing tadpole, except Nettie and Shadowheart.
Since you claimed "its hinted many times" it should not be a problem.
The issue is that for what content we have in EA, all roads lead to Rome. Rome being The Goblin Camp and saving Halsin. It's an issue of incomplete content.
The Grove is the main place that sets in motion which direction you will take. Zevlor, Nettie, and even Kagha herself convinces you to find Halsin or "help the Tieflings". As the first hub of the game, it feels like very strong encouragement when 3 different plot threads push you in this direction.
As far as Companion opinion's go:
Shadowheart makes it clear that she believes we need to find a healer. This will lead us to Halsin.
Wyll's condition for joining the party is killing the Goblin leaders. This will lead us to Halsin.
Astarion makes it clear he is not looking for a healer, but he is chaotic. He's the closest companion to being on board with siding with the Goblins, but doesn't hide the fact that goblins are vermin and that the Absolute might not be something we can twist into our favor.
Lae'zel's lead is to find the creche and shuns all healers including Nettie, Halsin, Sazza's Goblin Priestess, and what she assumes is ghaik-like trickery of the Absolute. This leads you to making a bee-line for the Gith Patrol whose conclusion is not in EA.
Not sure about Gale.
The only 3 paths that make sense to siding with the Goblins are:
1) sneaking past the Grove entirely to make it so Minthara is somewhat the first lead you get.
2) you are implied to be desperate enough or distrust the other leads enough to pursue the lead of a Goblin Priestess
3) you are enamored by the siblings deference to "True Souls"
And for the above situations aside from the first one, you'll encounter so much side information telling you its a bad idea that you have to play a specific brand of powerhungry chaotic evil to do so. And even still, once you murder the Grove, the benefits of the action are not in EA. The alternate Shadowlands passage and the drow controlled Moonrise Towers are not yet in EA. You'll probably have the easiest time taking that route, but for now it's definitely not a convincing route over just saving Halsin who has attempted to actually study the tadpole.
