If you start from a position of strong support for broad legal protection of "intellectual property", I can see that there would be an argument that a programming language as a whole could be locked up by a patent. As a possible analogy, (my understanding is that) Lego held a patent on the bricks at some point, and no clones could be produced because of that.

Like you, I would have a pretty hard time being convinced that this was actually a good idea, though.