Defamation to me would be lying about someone. Not musing. In order for it to be a lie you must know it's not true. It's a form of fraud. If you suspect someone is involved in a conspiracy there's nothing wrong with stating that suspicion and what makes you think that way. If you know it's not true, or you give weight to your suspicion by citing a source that doesn't actually exist or something like that, then yeah, I'm ok with people seeking damages for defamation.

That said, having not watched this trial and the evidence presented, I really have no opinion on how this trial should go. My post presumes that Alex was merely musing. If he wasn't, then yeah, I think the families could have a legitimate case.