Of course. But that doesn't stop anyone from writing their own interpreter that interprets the same language, as long as they don't copy any copyrightable parts of your interpreter to do so.
(Such an interpreter would likely contain a table of function names. The effect of this ruling is to clarify that that set of function names can't be copyrighted, so the alternative implementation of your interpreter can copy it. We already knew that the names themselves couldn't be copyrighted, but this ruling clarifies that also the "structure, sequence and organsiation" of those function names can't be copyrighted either.)