Intentionally causing a person to fear harm is assault. Greentext is committing assault. It might not be possible to convict for it, but it's still assault.
No it isn't when there's probable cause. And "dude started running after me" is enough for self defense to kick in. Actually it is probably enough to charge the dude.
It’s more than just “a man within range of vision”. Obviously we don’t have the full story here, but even in the text, there are specific behaviors that would, arguably, make a reasonable person suspect they were in imminent danger. Depending on the state, that is enough to trigger self-defense definition.