He probably ordered him to tell him his name and he couldn’t — so he shot him.
Or maybe the guy was walking towards him and he told him to stop. My speculation seems a bit more likely than yours.
Just declare the homeowner guilty and be done with it. If we’re lucky he’ll get Zimmermaned by the President and the Media.
But your understanding of the meaning of the word "mute" is not.
A "mute" is someone unable to speak -- not someone unable to hear.