Possibly because life isn't black and white Dolph. We have no idea why the lad was drinking so early in the morning. What we do know is that he's been working a steady job for a considerable time, and was apparently the best worker there. So we can assume that there must be some sort of negative influence.
To compact whatever that is by ratting him out, unnecessarily, is imo anyway, a contribution to someone's downfall. I'm not sure what world you live in chap, but contributing to a man's downfall (by actually driving him the length of the journey to work, whilst knowing you were goign to have him fired..) seems to me to be rather callous, if not rather cowardly.
There's nothing to have stopped the OP from turning the car around and suggesting strongly that the young chap take the day off, get himself together, and learn his lesson - aside from your nonesense "committing an act of misconduct", which frankly, who gives a crap about.
Act of misconduct, christ almighty dolph, show a little compassion.