Let's change the story; all other facts remain the same except as below:
Dog sniffs car, finds several hundred pounds of explosive in trunk. Suspect Izsheit Midrawrz confesses that he is to be taking this to a suicide bombing of a local school.
Do you now feel any differently? Or should the cops have let him go?
Be careful; constitutional search and seizure law is entirely written based upon the objective observations of the cops at the time of the search. You cannot justify a search based upon its results.
Oh you just had some pot, we'll let you go, but it's OK to pull you out of the car and beat you if we later find some guns or something dangerous. Sorry, I can't justify that legal reasoning.
Do we know if their drug dog would have picked up explosives Do dogs key off both types of items or are the different dogs for different categories?