released, but??

Someone I know was pulled over in Oregon for speeding on a major interstate. The (small city, not state) police said he was going 72 in a 65, but I know for a fact he wasn't speeding. He's simply too smart to do that. Worst backseat driver ever - he does not speed.

He asked to see the radar gun and the cop went to retrieve it. He returned and said it had already been cleared. The cop then proceeded to ask if he has his "green card", which he doesn't. He was then asked to sign a permission to search the vehicle and my friend declined. The cop called for backup and proceeded to search his vehicle anyway where he found product, grow chems, green dirt and cash. He was arrested. Possession, intent, manu, etc.

He spent a day in the city jail, was taken to county then released 1 1/2 days later. He was never arraigned. He got his wallet, credit cards, etc. back but nothing else. The police still have the vehicle as well as some irrelevant personal items.

He had a (very) large quantity. Why would they let him go? Might it have been dismissed since the arresting officer couldn't show probable cause since he cleared the radar? Or he may have been profiled; if his plates were run, his name would show a prior - could they have been cherry-picking?

At this point it's a waiting game. He's filed paperwork to get the truck and money back. He can't afford to retain an atty at the moment, especially since nothing's happened (it's been over a month now). He hasn't heard a thing from the courts.

He's just thinking he got lucky, that they have more serious drug offenses to prosecute (like meth). OR perhaps they're investigating further, escalating it to the DEA, since he does own property all over the west coast.

Has anyone heard of anything close to this happening? Why would they just let him go?