My XA also wanted to drink NA beer and everytime he did it ended up in a relapse.
High tech brain imaging now confirms that when addicts "see" bottles of beer, wine or hard liquor it actually fires off in their brain... lights up the circuits" and start releasing chemicals that bring pleasure.
Thinking about drinking gives them the mini buzz... and of course they want to feel that icy glass in their hand and smell that beer smell as it enhances and releases more brain chemicals that bring that pleasure.
Oh yes... it is a slippery, slippery slope and those that choose to jump on it with ice skates on are flashing neon lights "I want a drink!".
You are wise to be questioning this behavior. It is not a decision of someone who is in a strong, dedicated program of recovery and if your mate is white knucking sobriety the odds are strongly against his success long term.
Be very careful before making a life commitment with someone who is not dedicated mind, body and soul to dedicated recovery for a lifetime.