I would still call them "single issue voters" because they evidently put most of their eggs in the pro/con evolution basket. To me it's about the same "scaling" as an feminist voter, pro-lifer, environmentalist, etc.
It seems everyone's got their buttons - but when taxes and spending are on the line those buttons can get mighty pricey. And when it's national security, the cost can be unbearable.
It's not about evolution per se. It's the attack on all science being mounted by the conservatives (and their post-modernist and new-age allies) that people find a problem. It leads to a complete distrust of those in the GOP. Just like one couldn't trust Clinton (because of his habitual lying), many cannot trust the Republicans because they get science wrong. Thus many feel that the GOP cannot be trusted in things dealing with medicine, weather, technology, etc.
Scientists are not a large group. Perhaps the GOP feels as Jean-Paul Marat did when he said, «La République n'a aucun besoin des scientifiques»
Note that there are many people who distrust the GOP to make intelligent decisions on national security. With the anti-science bias shown by much of the GOP, they particularly don't trust the anti-missle system.