For me, a programming language is closer to mathematical notation than it is to a natural language that people use to communicate with each other. It's rigorous, logical, and typically the product of one entity rather than a natural language which is the product of everyone who uses it.

To put it another way, since the quote mentioned this, I don't think it's fair to compare a dictionary for a natural language to a dictionary for a computer language, because they're quite different things. One records and documents a process already happening [language evolution], while another is the process itself [language creation].

Just a personal opinion, that's all -- I just think analogies can be stretched too far, and by calling computer languages "languages" I think it's backed the discourse about them into a corner a little bit. Which is not to say all comparisons between computer language and "normal" languages are wrong, just that they're not really appropriate in this instance when discussing copypwritability.