USA-wise, it can be complicated with 1st Amendment rights. A website also has legal responsibilities. Where the line of distinction between the two lines is up to interpretation of the law and the ingenuity of the attorneys involved.
Cyber-bullying
IIRC, others were maliciously slandering him, according to Beta's interpretation. Of the posts I read after Beta left were a bunch of low blows and not uplifting, to say the least. He may have cause for investigating slander. That said, at heart, I tend to agree with you. This is a no-holds barred website. Dishing it out and taking it, go hand-in-hand. No excuses.
Legally, though, powers-that-be may have their own understandings. That is up to Beta's and WG's attorneys, if they employ attorneys. After that, it may come down to a judge.