That takes for granted what it should instead prove. Pinker, regardless of who he fraternizes with or what moral causes he supports or not, is an acknowledged scientist.

>Let's listen to them instead of the creep who hangs out with rapist pimps.

Who people hang with is irrelevant. We don't and shouldn't change who we listen to on technical/scientific/etc matters based on their personal morality (even less so based on someone's idea about that). We change who we listen to on those matters based on the quality of their arguments and domain knowledge.

In any case, we should not bring moralizing and posturing into discussions and into who we listen to, except if the morals in question are related to the subject matter.

E.g. I would be suspect to economic arguments from an economist who has been found to take money from states to push some agenda. But I wouldn't be suspect to economic arguments from someones who enjoys killing kittens. I just wouldn't take environmental / pet advice from that person...