I think Tula sees it as him doing something that was within his nature. It's in her nature to protect and in his to be curious about the blue. I also think she's trying to instill that he didn't want to die and that stotes die all the time doing all sorts of things and that if he had a choice, Geoffrey wouldn't have died at all. I also feel that since she doesn't know how he actually died, she doesn't feel justified in condemning him for it. For all she knows, he could have died foraging or simply walking home in the snow like she did. I feel if she saw him die by touching the blue or something like that, she might have had more anger about him dying and felt that he chose the risk, but since death is an everyday possibility of their lives even in the most simple of things, and as she says they are just stotes. She can't rightly condemn him for something that is inevitable and that she has done herself.