I agree. "Talking to him" isn't likely to help. I worry about any possible grandchildren I might have, but my sons have had therapy.
Just be wise about how you treat the children, especially when they are around you. For good or bad, I've seen some grandparents who have taken over the parenting role, even becoming the "real" parents by law. I know one case where the dad was an out-of-control alcoholic and agreed for his parents to raise his daughter.
Keep us informed, if you want. We care.
P.S. What's the role of the mother in this situation?