Yeah it's always better to be safe when it comes to that combo. I've had some ridiculously ugly experiences mixing benzos and alcohol. Felony ugly lol.
One bud light is 330 ml at 4.3% alcohol content, meaning there are about 14.2 ml of alcohol in it. On average your liver metabolizes one ounce of alcohol each hour, 14.2 is half an ounce, so it would take half an hour, one to be safe in order to metabolize it.
I would say he is plenty safe. You are also not taking into consideration the bacteria in your gut "produce" alcohol from the food you digest, so in order to be safe according to you, one would have to not eat any carbs during the day before using benzos. Which is ridiculous, as you understand.
You're in safe territory after 3h have passed and you've taken a bud light, however if you had 10 bud lights, I would certainly avoid taking clonazepam.
Yeah man that is really responsible waiting that long. Have you tried some of the more expensive german imported beers? They are awesome.
One brand of beer that is especially awesome is finnegans dead irish poet. It's a seasonal beer that is only available in winter.