I'm posting a link to the article, because OP is a Lib who doesn't post sources; but there is no way in hell that a he can make a credible self-defense claim in this situation, certainly not in New York at any rate.

The 24-year-old passenger stepped in after the vagrant, identified by sources as Jordan Neely, 30, began going on an aggressive rant on a northbound F train Monday afternoon, according to police and a witness who took the video.

“He starts to make a speech,” freelance journalist Juan Alberto Vazquez said in Spanish during an interview Tuesday, referring to the disturbed man.

“He started screaming in an aggressive manner,” Vazquez told The Post. “He said he had no food, he had no drink, that he was tired and doesn’t care if he goes to jail. He started screaming all these things, took off his jacket, a black jacket that he had, and threw it on the ground.”

That’s when he said the straphanger came up behind Neely and took him to the ground in a chokehold — keeping him there for some 15 minutes, Vazquez said.

Of course the article itself buries the lead that this is not some random asshole passerby, who you could reasonably doubt wouldn't know that putting someone in a headlock for an extended period of time is absolutely lethal.

The straphanger — who sources said is a Marine veteran — was taken into custody and later released without charges. The investigation is ongoing and authorities were waiting on autopsy results before deciding whether to pursue charges against the younger man, sources said.