If you take the default attitude that every academic is devil incarnate, then look at their argumentation separate from their character, you should be able to stay more objective.
So why the outrage over another bad guy? I think the obvious answer is some things are to the public conscience more terrible than others, at least at a given moment, specially if they are in the zeitgeist.
As for the weight of the testimony, that should be up to the judge and jury to decide whether it was valid. I mean, lots of these high dollar defenses rest on semantics rather than the spirit of things (tax cases, etc).
The Epsteins of the world will always have a tremendous amount of legal resources at their disposal. I wish we lived in a world where the people like Pinker would lend aid to those wrongfully on Death Row or perhaps the economically downtrodden, rather than ultra-wealthy college donors who got jammed up in what looks like, if not for their tremendous wealth and legal resources, something that should be a slam-dunk case.
To be very clear : Epstein is obviously guilty of some horible crimes. Pinker, seems like he crossed paths with Epstein and now people are out to get him.