Had a quick glance at this study. Forgive any mistakes, but I have a few “faulting” observations:

• over a third of the sampled people were people seeking immigration to the US. It could be argued that it could be argued that this points purely to the type of conservatives that seek entry outside their home country. Not the general population of conservatives.
• this study only looks at a statistical correlation. It’s dangerous to infer causation from correlation as correlation does not equal causation.
• intelligence measuring as had a long and troubled past. For instance, some tests were used to “prove” black people dumb. Turns out these tests relied on prior knowledge denied to black people. It can be very difficult to account for culture.
• maybe the tests used in this study only measure for people that are good at taking tests.