>> Imagine if English were owned by a vendor
In many cases it is.
The script for "The Godfather" is not in the public domain.
It's not the language that's protected, it's the application of the language.. or the compiler that's protected.

Computer "languages" aren't really languages.
They're tools we use to make a computer- another tool - select and execute commands, from a limited set, in a specific sequence.
In many ways, C# has more in common with a sledge hammer than it does with English.
If someone could invent a sledge hammer that was good enough to earn a patent, that person would be entitled to the benefits that a patent affords.

That said, the syntaxes of many computer languages - BASIC, COBOL, Assembler, FORTRAN, C etc, are essentially in the public domain.
In their cases, it's the compiler and the IDE, not the syntax, that make the tool useful to the user.
If I can write a whiz-bang FORTRAN compiler and IDE for Android that let the user make it, as Damon Runyon would have said, squirt cider in your ear, I'm entitled to try to protect them.