[ The damage is done, but identifying those responsible still matters. Retribution for all those lives would only be a personal reason, there's more than that. It's information that can potentially be used, whether in the form of the truth or manipulated in a way to get the needed outcome. And it helps him figure out where this person or people stand.

Geralt doesn't have much of an answer, but the detail about protecting the natives gives some context to consider.

At the question he raises an eyebrow. ]

You mean the queen's mage? As much as you expect. [ Which is, next to nothing. ] They said his protections failed or backfired. [ He shakes his head. ] If they suspected anyone still within the castle...

[ They wouldn't have escaped the queen's rage. Maybe it's cooled since then, but he remembers her eyes that day she burned a city. ]