If the officer simply jumped Garner, without any provocation, and without any clear instruction to follow, then the Professor might have a leg to stand on, with his proclamations of how the officer should be tried for manslaughter. Garner instead was beligerant, and refused to comply with officers' clear instructions. Garner escalated a situation that directly brought about the circumstances to his unfortunate death. Not the officer, but Garner. The officer, being an officer of the law, enforces existing law, passed by the legislature.
Regardless of how may times its repeated, Garner was not killed for selling illegal cigarettes. He was accidentally killed, when he failed to comply with officers instructions, that brought about the response officers had to use to force him to comply,.... that combination of that stress applied to the his apparent weakened cardiac status, as reinforced by his huge endomorphic body mass, brought about his tragic death
Had he complied, he's still be alive today