Dot must have second sight
Or he read the script. He had no idea that Lindsay was going into that Inernet Cafe to access the duplicate List that Danny had left there. For all he knew she might have just been emailing a friend or looking for a job on the net. And how did he know that he had impersonated a police officer, he was in the car and didn't come into the cafe?
Answer: he didn't. So why was he waiting outside, why did he prepare the car with false plates and why did he have the gun?