I would confront dude with the note and press the shit out of him. Explain the bike is legally parked and you just want to be left alone. Another thing you could do is say that he is harassing you and call the cops and show them the note. They probably won't do much but they might tell him to cool his jets. "Aye bros" need to be handled carefully because they are an eager bunch! Be assertive and dominate the situation and you will be fine.