HUH You suspect the man to not pass a DUI so you would let him make a call to get picked up. LOL
Ok so now you do that and you are called to an emergency do you ignore your call or stay with him so he might not hurt himself or others.
Of course you do the field test and if he fails you arrest him, Good grief what you want is ridiculous . You do not even want to enforce the laws.
Our founders knew justice had to be balanced by mercy and grace because humans are bent towards sin and no one can keep the law. Brooks was not endangering anyone, and a DUI today is devastating by itself, even without prior knowledge of his criminal past.