Breathalyzing & Underage Consumption of Alcohol - SWIM's friend needs your help!

[Nacumen]

Yesterday SWIM's friend was drinking some alcohol, 3 beers to be exact. SWIM's friend spilled some of the beer onto himself. SWIM's friend then rode (not drove) in a car and got pulled over by a cop, who smelled the alcohol spilled on SWIM's friend, and breathalyzed SWIM, coming up with a 0.046 BAL.
SWIM has heard that the natural levels of alcohol in the human body hover around 0.030. Would SWIM have a good case in court if he were to fight the offense, saying that the reason he emitted more than 0.03, 0.046 to be exact, was because of a few doses of 5% alcoholic cough sryup he took? Or does the breathalyzer not pick up on the normal levels of alcohol in the human body, making the 0.046 too far fetched to be achieved by a normal couple doses of 5% alcoholic cough syrup alone? Also do take note that SWIM's friend did not tell the cop that he had taken this alcoholic cough syrup while he was being breathalyzed.

If SWIM's friend chooses to fight the offense, he could be charged an additional $1-1000 past what he would if he admitted he was guilty, if the judge does not buy his case of using alcoholic medicine. If he chooses to fight the offense, there is also a fairly good chance that the cop wont even show up to court to testify against him, which would mean the charges would be dropped anyway.

If you could tell me your opinion of how you would suggest to proceed, it would be greatly appreciated.

Thanks,

Nacumen