> I worry that people read studies like this and suddenly justify going out and driving while impaired

I don't know about that, I think the people who want to do that will just find another excuse. Especially potheads, who seem to be unable to acknowledge that anything exists in this world that isn't helped by pot. Driving? probably better if you do while high. Seizures? Pot is now the only accepted option man. Broken back? Here have a pot brownie.