Your analysis is ridiculous.
No, your bizarre cop game of "Tag - You're Dead (If I Feel Like Killing You)" is ridiculous.
1. Walter Scott bolts from the car. He's not a fleeing felon. He's not assaulting Michael Slager.
2. Michael Slager decides rashly to give chase.
3. Michael Slager catches up with Walter Scott, and touches Scott in some way, shape or form. Remember, Scott is running away - he's not trying to confront or assault Michael Slager.
4. Walter Scott perhaps shrugs Slager's hand off, or pushes away from him. Scott is still running away.
5. According to you, this mere act, however innocuous, INSTANTLY turns Walter Scott into a "fleeing felon". Now Michael Slager can kill Walter Scott, if he feels like it, according to your bizarre logic.
6. If Walter Scott outruns Michael Slager, and Slager is not able to "tag" him, then Walter Scott is just some guy fleeing the police, which I believe is a misdemeanor.
Hang on a second - you don't believe that the mere act of fleeing the police is an automatic felony, punishable by death at the pursuing officer's discretion, do you?