Hi, VN.
It doesn't matter if it's beer or vodka. It's all alcohol andd equally detrimental.
As to helping your friend taper, I would be very leery of being put in the position of alcohol police.
It would be hard on both of you.
You are not the only one who can help him.
You are the only one HE wants to help him.
I would keep talking about medical detox, stressing that it is the safest and most potentially successful way to go.
I also don't think your friend is ready to quit yet, hence his reluctance to go to a facility.
He, like most of us, probably cherishes the idea that he can drink "normally."
Peace. Good luck.