Garner may have had no knowledge of his medical condition beyond the obvious weight issue.
That said, compliance should be the first order, but we live in country where certain demographics are encouraged to resist by government leaders. Someone like Garner was probably raised on NWA F' da Police, and 187 on a MF'n cop, so he needs little encouragement to be difficult. As such, it's up to the 'adults' to handle the situation in manner that cleans up the mess and leaves no unsightly residue.
It’s possible that he didn’t, but I think it is more reaosnable to expect that he would have such knowledge versus expecting the police to have such knowledge.
And I would agree that it is likely that cultural influences played some part in his decision to resist.