It’s not a question of offense. It’s a question of the word having no meaning.
Fleeing from a cop doesn’t create reasonable suspicion of being an illegal alien. It creates probable cause that a crime has been committed in front of a police officer.
So, you’re the one assuring us that it’s so obvious how reasonable suspicion can be created, and the rest of us are just rubes who can’t figure it out. Can you give us a scenario where no other crime has been committed, an illegal has declined to answer whether he’s a citizen, and there exists reasonable suspicion to continue the inquiry as to his status?