Perhaps so, to some extent: you may like it or not, but guilt by association is a successful political tactic. But the problem is made even worse by the fact that his writings occasionally support the Greens' nasty attitudes.

To take the analogy even further, imagine a respected scientist writing approvingly about "deep ecologists" and "Soylent Greens", who believe in the primacy of natural wilderness, and argue that human societies are inherently evil and inimical to true happiness, excepting "naturally co-evolved" bands and tribes of low-impact hunter-gatherers. Such a belief might even be said to supported by evolutionary psychology, in some sense. But many people would nonetheless oppose it and describe it as nasty - notably including more moderate Greens, who might perhaps turn to other sciences such as economics, and think more favorably of "sustainable development" or even "natural capitalism".