There was an urge to say that no, Sigyn was nothing like Frigg, younger or otherwise. If she were, Loki wouldn't be pining after her, because there was nothing about his sister that the Trickster liked. But Thor loved her, so he didn't say it. Even with the reminder of her ambition, which led her to cut Jord in ways that were unforgivable.
Because he hadn't really forgiven her that, he did say, "Everybody's got some of that though, don't you think? You just said she likes to be independent. Who doesn't? Just some more than others, I s'pose."
Then he couldn't resist teasing her a bit, since he'd shot down her theory on Sigyn being like her. "And I thought the whole reason we were doin' this was to set 'er up with Magni. Thought you were kidding about the other guy, 'cause he sounds like an idiot. She'd be a good daughter. I think I'll keep 'er."