It's not the police officer's "job" to pepper spray people during a nonviolent protest, whether they're in the way or not. It's their job to use restraint.
You seem to be suggesting that police should not get to do whatever they want to a person simply because the person is in violation of the law. In justice circles, this concept is often referred to as "proportionality". I.E. If a crime is being committed, the response of the police should be proportional to the crime being addressed.
You also seem to be implying that police officers should be held to the same standard as the rest of us. Like you and I, a police officer may not take an action simply because:
a. They really want to do it, and
b. They think they will get away with it.
In my mind, such practices would allow people to do things that may excite or annoy others, as long as they remain within the bounds of the law.
For example, in this country we believe that a woman should be able to wear a short skirt without fear of physical or sexual assault, even though it may excite or annoy nearby people (i.e. men). I will refer to this concept as "being legally responsible, even though you really wanted to do something you should not"
In this country, many people also believe that non-violent, law abiding protesters should be able to exist, even though their existence may in some way excite or annoy those nearby (i.e. police officers).
Both ideas "proportionality", and "being legally responsible, even though you really wanted to do something you should not" seem like laudable goals.
For better or worse, the change on Nostrand is going to make the change on Franklin look minor.