[He understands Jaskier's discomfort with collaborating with the factions this way. They are being used, and Estinien has no argument to the contrary. He's used to being a tool, though - it's a part he can play. At least until a point. He doesn't think it's possible to get what he wants here without at least putting something on the table.

But he definitely doesn't think that Thorne has any more authority on this matter than Solvunn does.]

I wasn't trying to kill her. [At least, not initially. When she answered in kind so enthusiastically things had clearly gotten more dire than he'd hoped for.] I'll have you know that my first attack, measured so to avoid such an outcome, did absolutely nothing against her. 'Tis a struggle to pull one's punches against a power like hers... anything less than my all and I was crushed beneath her heel.

So, what are mine alternatives, I wonder? [And as he says it, this is clearly something he's been thinking about a lot, and not just a lead in his to his argument.] To allow her, and by extension Thorne, to have her way, no matter the cost? After all that happened with Geralt, attempting to convince her with words would be an insult to her conviction.

[It would be plainly stupid of him, he thinks, to simply ask Yennefer to abandon the casket, when she had already either participated in or allowed for the torture of someone she ostensibly cares for as part of the same political gamble. To get into Thorne's good graces, for whatever end. If someone were to lure her from her path, it would certainly not be him, but that doesn't mean he will surrender to her will without resistance.]

'Tis because we know so little that I support Solvunn's stance of nonintervention towards the Singularity. It allows us time to learn before making a choice, which Thorne and the Free Cities' overt meddling may not.