I don't get the section on JSON, which seems to assert that XML is more secure than JSON. It does this by linking to a Wikipedia page that includes the security consideration that you shouldn't call eval on JSON. True, but at least that's a tractable problem. Your linter can check for code that calls eval.

In contrast, there are plenty of XML attacks (DOS with billions of laughs, entity references), and parsing XML is a lot more complicated, which matters a great deal if you're using non-memory-safe libraries for parsing. Also, because XML is so general purpose, you get things like libraries allowing deserialization of arbitrary objects from XML, which is a security nightmare.

That last point isn't a clean win because sometimes the same library will handle JSON and XML, and so you have to audit the use carefully. However, if you're sure that your serialization libraries only use JSON, its simplicity means that it shouldn't have that kind of deserialization vulnerability.

P.S. If you want to rag on JSON, that's fine. It's not a great format. But "it's less secure than XML" is not the tack I'd take.