I think in AA it is really hard to maintain one's safe boundaries, too.
Those who are still drinking are much more likely to have no sense of personal space and it is uncomfortable for me to be around that kind of energy. Being sober for a while in AA it was easy to learn the lesson that I should try to stick close to those who had some sobriety. The energy of the people who were still drinking was dark, desperate, and scary to me.
Maybe others don't get those same "vibes" but I know for myself, I was more cautious with active drinkers - and I limited where I would spend time with them, but I certainly wouldn't ignore them or judge them out loud. I do understand why people would give this man a wide berth, though. I don't even think someone has to admit they've been drinking, it's obvious.