Joseph, a “shtarke Ger” will want to do the ratzon Hashem. And maybe in his case the ratzon Hashem is to stay civil and friendly with the family, especially if the Rav encourages and advises this. Don’t forget, chillul Hashem is one of the most severe aveiros.
In any case, who ever heard of a ger who is not “shtarke???” If he was not shtark he would not have made it to this point!
I agree with cherrybim on this.