I think this a difficult study to have actually done. It would be very difficult to control bias. How does one determine if someone has a good understanding of Evolution? Apparently they just did a poll. Usually, if someone studies something, one at least broadly agrees with the content. Seldom do people continue to study a concept once they found something unacceptable or that they consider wrong. On average, a person with a good understanding of Christianity or Islam say, is more likely to be a Christian or Muslim. Most who study the Koran or Bible would do so with the understanding that inherent worth is to be found there. Muslims or Christians seldom study the Rig Veda. You would find the odd religious scholar, but broadly this would be the case. I have used religion as an example, but it would hold true for geology or paleontology or any of the sciences.
So intrinsically, someone that has done the effort to be able to have a "good understanding" is probably someone who has already broadly accepted the concept. This study does not really give us much useful information, therefore. It hinges on what is understood as a "good understanding", but I believe the study has inherent problems of presupposition and bias that renders it fairly moot. It would be a different matter entirely if they gave a randomised group instruction in Evolution and then determined their acceptance thereof, but to retroactively try and correlate acceptance with understanding is going to presuppose that they are broadly equivalent, by its very nature.