from someone who as BTDT-bought-a-tshirt, i think that drawing down on an unarmed person simply because they look 'scary' and are walking towards you is a bad idea.
unless you are cornered with no way out, i dont think that even brandishing your weapon is going to be considered 'justifiable'. would depend on your states laws regarding the use of deadly force and whether or not you have any duty to retreat, or at least make an attempt to.
"Every man alone is sincere; at the entrance of a second person hypocrisy begins." - Ralph Waldo Emerson
"People demand freedom of speech as a compensation for the freedom of thought which they seldom use." - Soren Kierkegaard