As the discussion of which group Aldous will attend, Stella's mind goes back to Ajantis and others' comments on how much Aldous seemed to be swayed by her influence. If she didn't say anything, it might be hard to change his mind. She hated the idea of having so much sway on him...but if it helped everyone, then she'd use her influence.
"Aldous' arcane aid proved extremely valuable when we infiltrated the Iron Throne's mine," she begins.
Stella really wanted his support...but he did keep throwing himself into danger. And it was probable they would get distracted for fear of each other. They still only had a small amount of experience working together.
And she trusted Aiwë. She understood people better than Stella did and had supported her throughout this entire journey. If Aiwë thought Aldous work with his father, even if Aldous found it tedious or hard.
"If we're doing a stealth operation at their headquarters, however..." Stella continues tentatively and meets Aldous' eyes. "...a smaller group is likely better," She thinks to Duke Eltan's earlier comments. He did have a good mind for this kind of thinking. "Additionally, your insights could also be valuable for the dukes, as you have much firsthand experience with the kinds of mercenaries they hire and have seen their operations firsthand," she smiles reassuringly.