Admitting is fine, the problem is when you pass by people on the street and don't talk to them at all. A family member of mine has made enemies from people who assumed she was slighting them on purpose. Nowadays she actually explains her condition to new people she meets.
That's self important people thinking they can demand attention by simply existing.
There's no either/or in the kind of situation. It isn't EITHER "you did recognize me and avoided me on purpose because you hate me, and we're enemies now" OR "you have a debilitating disorder and are blameless" because that puts the recognizer on trial for a crime, in a world where failing to kiss the ring breaks the law.
Truly, it's not a crime to blow past people while you're in a hurry, and the enemies your friend made are simply demanding assholes.
I've had the inverse happen, where I see someone's evil twin doppelganger, stare hard at them, walk over, and then... Oh! It wasn't them, it's just a total stranger.
Recognition and social grace don't have hard rules. Same goes for being late to work. If you have some dick boss who fires people for failing to have their ass in the chair by 9:01 AM, better to break that rule hard and often up front, and find out that the boss is tyrranical overlord, and get fired in a week, than live on for years with the spectre of doom hanging over your head.
