There is zero hard information of any type.
What percentage of the traffic was spam or harassing? Was it 10%, 1% or 0.0001%? How much effort did dealing with this take? Why couldn't the spam protection mechanisms of gmail be used to the same purpose?
If they wanted to be transparent at the time or any time since, they could. It has been proven in court repeatedly that Google are deliberate monopolists. There is no reason to give them the benefit of the doubt.