He is returning JSON cause doesn't understand the specification, just like you.
I don't know his intentions but I'm very sure I know about JSON-RPC. What you seem to be unable (or worse, unwilling) to understand is the fact that RPC is not tied to a specific standard.
http://en.wikipedia.org/wiki/Remote_procedure_call"Many different (often incompatible) technologies can be used to implement the concept."Why are you so focused in JSON-RPC? He didn't even mention it once.