I sort of feel that if this anonymous posting was 100% accurate, then the cofounder wouldn't have resigned. Better if the people involved came out and told the truth.
Not necessarily. Even if Horvath was the original bully, inappropriate retaliation can still get you fired.
Also, it may have come out in the investigation that the founder gave his non-employee wife way too much inappropriate latitude inside the company. She's conceded that she went too far with her activism around her startup. But especially if she crossed boundaries and had inappropriate access to private company information (as Horvath said she claimed), the founder could take the fall for enabling that.
If his statement is to be believed then his resignation did actually have nothing to do with JAH's allegations. I'm not saying that anyone is lying here, just that the anon posting is plausible. I agree with you that it would be better if everyone just told the truth.