From my understanding, anyone can go get a drink there (I actually just watched this on one of my favorite Disney Vlogger's post about the Wish - Mammoth Club ) - you don't have to have a service booked there to get a drink, so you'd be welcome to tag along.
They definitely do serve drinks in the evening and the salon is still open. You would just want to book the shave between 5-8. We did a b2b2b and my Dad got shaves on each of the 4 nighters while my Mom and I had a drink.
It was funny because one day the shave was running a little behind schedule and we had the speciality whisky/bourbon seminar in hooks. There were only 6 seats in the class and the other three people showed up early, so we told the bartender to get started. My Dad enjoyed the first of the drinks in the salon chair and then joined my Mom and I upfront for the remaining drinks.
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