Well here is surprise for you. I used to be a scientist myself. Just in a totally different area. From my experience being racist and impartiality to results in one's profession are orthogonal.
All the arguments I see so far are of "but, but he cheats on his wife" quality.
This isn't doubting someone's opinion because of a completely unrelated character trait. Taking your examples, if he was cheating on his wife or eating babies (?) that probably wouldn't have any bearing on this. I think the issue people have is that someone with pretty questionable opinions on race has got some other opinions on a hot topic that has been tinged with racist rhetoric from the right. I can totally see why that'd be enough for some to pass on it and say "nah, no thanks".
All the arguments I see so far are of "but, but he cheats on his wife" quality.