No, you didn’t leave it open. Here are your exact words.
“He slandered the parents by claiming that they were in on the plan to slaughter their children. He didn’t ask if they were or leave a shred of doubt by stating that they might have had a hand in it. He said outright that they were involved.”
He could sue you if he has time. Because you cannot present any proof of your fantastic claim.
I said had he kept it open, they couldn’t have sued. However, he crossed the line sufficiently where he left himself open. They were able to demonstrate harm and judgement was rendered.
I’ll be waiting by the phone.