Except if you are actively dying and I refuse to help in my personal capacity, I’m not threatening to harm you. I’m just not helping you from imminent harm (presuming I didn’t cause that imminent harm). Now if you’re on fire and I’m currently watering my lawn with the hose when you ask for help, it’s shitty of me to not help. But if you’re in a gunfight with someone and you’re asking me to render aid as they are still a threat, sorry pal.
E: Apparently some ignorant idealists don’t like making a distinction. Tough shit. From a legal standpoint, that’s how it works.
That is a “good Samaritan” law. They can compel you to help, but that could be calling law enforcement. That’s also why in my examples the gunfight still had a deadly threat. No laws compel you to put yourself in danger to help.