I see what you mean, and it actually is a good point. I learned how to do that at school, and it's quite unbelievable how it works.
If you are given the language you're working with, you can translate a whole program into just one number, and translate it back.
I was told it is a method also used with cryptography. I did it with a 10 instruction and 4 keyword program, and it was quite easy. But i guess doing it with a whole C program, would make it quite hard. (although i guess the program could be automated)
Still, making a number copywrighted looks like a bit dumb to me.