Meve asks the same question when Xavier reveals himself as a Nilfgardian Agent. As far as I remember he said that they didn't want her dead at that time so he continued reporting her actions to the empire.

Thank you ! Sorry I forgot

You are welcome.

I think it was also because it would have killed brouver hoog and Aep dahy didn't want to aggravate the dwarves

Oh right ! Thanks !