It isn’t like Penny shot Neely. He restrained him. Neely may have died as a result of choking or drugs, but Penny did not intend to use deadly force.
There are reports that Penny continued the chokehold for 45 seconds after Neely lost consciousness and crapped his pants, and he continued the chokehold after by-standers warned Perry that he was killing Neely. While I agree that Penny did not intend to kill, there is certainly probable cause to arrest, charge, and present the case to a grand jury. But again, even if Penny did not intend to use deadly force, the question remains as to why Penny used physical force of any kind when by all accounts Neely did not attempt to physically harm anyone. NY law does not allow the use of non-lethal physical force to stop a person from spitting, cursing, verbal threats, and similar anti-social behavior that does not involve physical contact or attempted physical contact.