Using their logic he didn't mention his mother, so there must be some kind of hatred there too.
The correct answer is that Maureen and his father are dead now.
You may be right about the "hatred," but I doubt it. Michael may be a bit boorish at times, but I don't consider him a hater.
Perhaps it was merely an ad-libbed remark by Michael and he simply didn't cover all his bases. Though his speech was obviously heartfelt this night, and not to be too critical (the poor guy just buried his father, afterall), it wasn't very well delivered.