He has never said a disparaging word about his mother.
However, if you are a Catholic guy dating a Mormon girl, then remember that her parents may be averse to it. This is because if your relationship gets serious and you guys get married, then she may have to forgo many of the customs of her religion.
Whenever you bring something up, they'll say if it's not on lds. When you try to explain to them why the church would not publish said info on their own website they get mad at you and tell you you're ignorant.