I work with teens Michael Brown's age and the number one rule is

[alcibiades_mystery]

76. A person who has just committed a crime is more likely to avoid confrontations with police

Particularly seemingly unrelated confrontations. Perhaps your thesis stands if a cop actually seems to be pursuing a suspect in a robbery, but we don't see that at all in this case. We're to believe that somebody fleeing a crime scene actively sought a confrontation with a cop that would otherwise have been avoided. That's patent nonsense.

Johnson's testimony shows Brown's consciousness of "fleeing," when they see the police car race by toward the Ferguson Liquor and Market, and Brown tells Johnson to just walk normally.

Additional points to make:

Even if we bought your counter-intuitive thesis, the seriousness of the crime is a post hoc construction of the police and media. This is not to say that the acts in the store couldn't be construed or charged as a serious crime, but rather that we have no particular evidence that Brown would have seen it that way. Indeed, Johnson seems surprised in his testimony that the police are racing to the scene so quickly. If none of the subsequent events would happened, would the police have actually pursued this as a major felony investigation? Would a DA have charged Brown or sought a conviction for a strong-armed robbery? Unlikely.