In a way yes he did, his actions are what started the whole incident.
their intent was not to kill him but their actions were extremely foolish , hence manslaughter as opposed to murder. ANYBODY that has handcuffs should know that you do not leave them prone one second longer than needed. Even LEO's who can lawfully use deadly force to obtain an arrest know better than to use submission holds for 20min, if you can't get control within a minute or two you need to break contact and use a different method