I was never going to quit, but I can see why you might have come to the conclusion from the way I worded it. The only direct friction happening for me was during those deliveries. Otherwise, my contact with that employee was minimal. Everyone has the right to refuse to work in an unsafe environment, be it work conditions, equipment failures..etc.HR already had the paperwork going to ditch him and were just looking for a replacement.
Then you set an expectation with management and your prediction occurred like clockwork.
Icing on the cupcake was kid was observed imbibing and confessed in front of multiple witnesses; including a new owner, that he was stoned while on the clock and corroborated your account.
You got the information in front of decision makers in an environment where it could not be ignored or swept under the rug.
The new owner was never going to get a better chance to send a message to the entire workforce about their attitude regarding impairment in the workplace.
Sometimes the timing is the most important thing.
Sounds like it worked out for you..
Just one thought - what if they did not fire him and chose a lesser reprimand.
Were you prepared to walk?
Remember, if it had gone differently, and you did not quit, you would lose all power and credibility in future negations. The same is true if they believe you were bluffing and got lucky.
If anyone ever asks, you had something lined up with an old friend, and it's probably still available.