Obviously, I think this is a strange sort of way of deciding if a student has been productive enough to graduate. That said, I have to comment Professor Lou for honesty, at the very least. I'm sure lots of professors have informal policies that they'd very unwilling to write down anywhere, much less one's group webpage.
I also liked this little tidbit from his site:
Note: Please don’t contact me if you are not truly passionate about this type of research, or if you just treat the position as a job.
Well, okay, then.