While they are in the sneak position, they are clearly focused on the bear and pay no mind to you. UPDATE 12/2/13: The NPC will grow to hate you quickly if you do not wait til you have to sneak past the bear in the underground portion of Helgen.
As I mentioned above, that would be pretty challenging on your part if you are to attempt to progress through the game, so choose WISELY on what combat skill you wish to level up along with your sneak. Remember, leveling multiple combat skills + sneak can progress your levels quickly. The game progression shouldn't be that difficult, least not in my experience.
You shouldn't be any higher than level 25 with 30/40 ( combat skill) and 50/60 sneak. It would be best to train your choice of combat to 40, and sneak to 60 for that stealthy approach.