He may not care about the law, but the user of that unlicensed software will care when they get sued for using it.
"Oh, but I would never sue you for using my software" says the unlicensed GitHub author.
"But I can't trust you. You're not trustworthy."
"Oh, but I am. I won't sue, I promise!"
"Then why don't you put that promise in writing? It's called a License."
Because the author of this particular source code strongly prefers users who like them who are ignorant of the law? The author doesn't want to get sued for his license.
Another good reason for no license is a very nice and polite "go away". This is just to show I use social media to get a checkmark on some hiring list and get a job and has no purpose beyond that.
This is exactly why you don't use unlicensed code in any commercial application.
But I thought by putting it on GitHub, and claiming that he doesn't believe in licenses, because he wants EVERYONE to be able to use the code -- that he wouldn't then 'allow' a special friend to use the code.