Overlooked in all this discussion is this sentence from the original article: Current eligibility rules stipulate a player can only represent one country at full international level.
This wording is likely the crux of the matter. They undoubtedly equate "full international level" to "test" and the ARL recognizes only Australia, New Zealand, England, Great Britain, France and PNG as countries that play these. In their eyes there's a class system for countries and playing for a second-class one doesn't count the same as playing for one of these first-class ones. This explains why they don't care about Hayne switching to and from Fiji: to them Fiji's a second-class country in the game. The RFL is complicit in this too: Scotland doesn't play at "full international level," and therefore Danny Brough's appearances for Scotland don't prevent him from playing for England because they're looked on as second-class internationals.
This class system is a major problem for the game. It's what allows the country-hopping we've seen in recent years. It's created a situation where countries were granted automatic places in the World Cup even though they're considered second-class countries in the sport! It's pathetic and contemptible and needs to be abolished so all senior International matches are treated equally.