In a similar vein, I am Frum today because of someone who mekareved my mother when she was young and then went on to become Reform and an Apikorus and lead people astray.
I have no idea how Hashem judged him in Shamayim when he was nifter. But I do think that it was a Mitzvah that he mekared my mother and I am sure that he is getting schar for it, and I do think that I have to be makir tov to him.
When he was nifter, I told my mother that she should go be menachem avel the family so that they can get some nachas. They were very surprised to find out that he had ever mekared anyone and I think that it did give them some nechama.