Hmmm.
There are two issues. One is his performance. Two is his reference to drinking.
I believe they are separate. If you wish to professionally address his inability to 'lead', that is one thing. I would follow proper channels to do that. If he is the leader, does that make him your boss? If so, you might want to talk with HR. If he is a co-worker, I dunno. Personally, I would stay away from it and let his performance, or lack of, speak for itself.
The references to booze? I'd avoid that like the plague. You've chosen to be transparent. How he handles that is up to him. If you address it it sounds like the two issues will become entwined and that's a lose lose. Whether or not he has a problem with booze is irrelevant until he makes it relevant.
Just my two cents.