It’s just a regular npc. The Strange Man has different attire (black jacket as opposed to a black coat, grey vest as opposed to a red vest, different kind of top hat, etc). I’m sure if one were to look in the game files, this would be “Generic Saint Denis Gentleman #54” or something along those lines. Red Dead definitely has a lot of very hidden references, but generally speaking, it’s best not to overthink most npc’s we come across.