Finally got an answer:

"This was intended - we wanted the player to increase their risk of infection anytime they broke social distancing regardless if the NPC is actually infected or not since the player (like in real life) likely does not know the other person's status. The "player" tag in this case is applied to each NPC in the game, so it can trigger properly. We did debate this internally, but felt that this was the best way to force players to be alert about their position in the store and take social distancing seriously."