Automobile accidents happen every day and most are not drug related.
You tell me how hitting a fire hydrant and a tree IS probable cause....?
It was two in the morning, he may have just fell asleep at the wheel. Maybe he had a seizure. Maybe he had tire failure. Maybe the suspension gave way on the one side of the vehicle. Maybe a dog ran in front of the vehicle and he wrecked trying to avoid killing the dog.
Get the picture?
It was 2 something am. There were no other cars involved. He barely made it out of his driveway before he crashed. Plenty of probable cause for a DUI. A regular person would have been given a breathalyzer.