So HR finally called 30 min after the 1-hour window they initially gave him.
The two points they asked him about involved making a comment to the effect of his wife not wanting to have sex with him anymore (something husband often whines about to me when he's depressed and feeling neglected -- so it's not a stretch that he would have said this in a conversation with someone, though I doubt he would have announced it to all within earshot, and no it's really not appropriate conversation for the workplace, but given his impulse control issues, I can see it happening).
The other comment had to do with him making an observation that when people move to a foreign country, they very often settle down where there are other people from their country living, and he has voiced opinion in the past that he thinks this prevents immigrants from learning English and in his opinion, immigrants need to learn English if they're going to live in the U.S. I don't know the ethnicity of the ex-employee, but apparently he took these comments as contributing to a hostile work environment.
Personally, I think the ex-employee is grasping at straws. I think husband has problems knowing when to shut up but I don't think he has ever said ANYTHING to ANYONE with malicious intent and it would be out of character for him to do anything like that.
We'll see where it goes from here.