It's a tough call - personally I think the right thing to do is always to direct people to medical help.
None of us are Drs - it's pretty pointless trying to guess whether someone is drunk, very drunk, or in danger of DTs or seizures.
I know waiting rooms are full and the wait is long but y'know? I really wish I'd done that.
My last detox was pretty horrific.
Is this guy a regular visitor to your house?
D