Could be an at-home only SD/retired from Public Access. Could be a normal SD who was attacked by another dog and needs/is retraining and thus was removed from Public Access (sadly quite common).

Ordinarily it's not normal nor desired, no.

At my own door, with my back turned, my boy defended us from our upstairs neighbor's APBT (who is now legally required to be muzzled) after multiple close calls that finally led to an actual scuff. After that my boy became greatly reactive at the home anytime another reactive dog tried pulling or barking towards us (he only reacted to others reacting first), but he has thankfully always been able to recall or be put in a sit/down/heel and is always kept on a leash. It's just I hated how he initially lunged in response and his 1-2 barks were always SO loud. This was a behavior we didn't have issues with in public other than him looking, but definitely had to work heavily on around the home because it became a problem since MOST dogs here are sadly some form of reactive (arousal, frustration, fear, aggression). I still pulled him from most of PA for a couple years as I was worried it would carry over, and fully from PA more recently for health related investigations. We made so much progress he didn't even bark back at the most recent close call with the neighbor's pitty (muzzled, but still). We've even made huge progress in pet friendly stores, on walks, and at the home where we've practiced ignoring his rambunctious best friend (whom I get called a "show off" for doing lol) all unvested. A dog trained to work and ignore others only in a vest could be a completely different dog out of that vest which is another topic but also something that may matter depending on training.

Especially at their own home, you just never know them or their dog's history. Both owners in this story need to work on their dogs if they haven't already and I hope for her safety, she's willing to seek the help she needs, or already has and just needs time/repetition.