Yoo hoo, one has to decide what the law means to adjudicate a dispute under it.
"No institution other than the one that wrote the law can rightly determine its content."
The courts rightly apply the law to actual cases. It's their job. To do that they have to decide what that content means. When they do that they aren't "making law" in the sense a legislature does, and their decisions are based on the law as written. Those decisions do not lack constitutional authority, as the topic article suggests. Apparently the author isn't the only person so confused. But at least most people aren't off writing articles about things they don't understand.
Article I Section 1 empowers congress to write law.
If the content is not clear to the judiciary, it is up to congress, the lawgiver, to clarify.