To anyone who call Geralt imbecile for making this choice: I guess you don't remember books and previos games very well. In other case you wouldn't claim that Geralt would never make this decision.
For example, in "Lesser Evil" he decides to slaughter Renfri and her man to save people of Blaviken. Of course it is implied that at the same time he led to even bigger massacre of this very town. Renfri even mention that she would not kill anyone anyway, but he didn't know that. From certain point of view it was stupid decision, but still, even knowing consequences, he had to act. He realised that he would feel even more guilty, if it turns out that Renfri would do that. Is it a right decision? I don't think so. It would be better if he just let things flow and did nothing? Maybe, but later he find out that neutrality may be much worse then making a choice.
Here's another possible choice from the Witcher 2. When we find a female troll who's fighting with mercenaries we've got a choice to help her or help mercenaries to kill her. Trolls also eating people (in this case we know that for sure) and female troll killed some of the mercenaries already (it is implied that they attacked her first). In this case, if you decided to help her, he kill human mercenaries (who act quite respectful toward him) to protect people-eating monster and just let him go, because he doesn't seem harmful to other people on regular basis (trolls possibly were just eating already dead people). You noticed some similarities? If he was able to make a choice like that before, why assume that he wouldn't make it here?
Also he usually act impulsive. In short story "A Question of Price" he attack the queen soldiers on her very eyes to protect Duny without even thinking about consequences (and let's just say that consequences were quite impressive). If he weren't lucky, he wouldn't leave Cintra alive. This is also example that Geralt is willing to risk his life not just for pretty ladies.
For example, in "Lesser Evil" he decides to slaughter Renfri and her man to save people of Blaviken. Of course it is implied that at the same time he led to even bigger massacre of this very town. Renfri even mention that she would not kill anyone anyway, but he didn't know that. From certain point of view it was stupid decision, but still, even knowing consequences, he had to act. He realised that he would feel even more guilty, if it turns out that Renfri would do that. Is it a right decision? I don't think so. It would be better if he just let things flow and did nothing? Maybe, but later he find out that neutrality may be much worse then making a choice.
Here's another possible choice from the Witcher 2. When we find a female troll who's fighting with mercenaries we've got a choice to help her or help mercenaries to kill her. Trolls also eating people (in this case we know that for sure) and female troll killed some of the mercenaries already (it is implied that they attacked her first). In this case, if you decided to help her, he kill human mercenaries (who act quite respectful toward him) to protect people-eating monster and just let him go, because he doesn't seem harmful to other people on regular basis (trolls possibly were just eating already dead people). You noticed some similarities? If he was able to make a choice like that before, why assume that he wouldn't make it here?
Also he usually act impulsive. In short story "A Question of Price" he attack the queen soldiers on her very eyes to protect Duny without even thinking about consequences (and let's just say that consequences were quite impressive). If he weren't lucky, he wouldn't leave Cintra alive. This is also example that Geralt is willing to risk his life not just for pretty ladies.