Rules as written, it does not. It doesn't qualify as armor any more than a barbarian or monk's unarmored defense does, or a druid's barkskin. An alternate way to think about it is that it doesn't require any of the armor proficiencies.
While the rules are clear, I don't see it as unbalanced and would allow it if a player at my table asked. But that would be a house rule and not something to fly at an AL event.