Whether or not it is legal is not the point. It is dangerous to ride on the sidewalks and best avoidedd altogether. People on foot step out onto the sidewalk with no expectation that a bicyclist is going to go be at 15 mph and so there is a very good chance for a collision and serious injury for those involved.
I use my brain to decide what is safe and the legality is not a consideration. What is legal for bicyclists is often very dangerous and I prefer not to needlessly risk my life and limbs. Traffic tickets by overly zealous cops are far cheaper than a visit to the emergency room or the morgue.