It wasn't from a reliable source so I discounted it... but I wonder if it came about in a similar manner as the discussion we're having today - stemming from the idea of "ruins" being involved on the ride? I can see why someone would jump to that conclusion...To be clear, I've never "heard" about this taking place after BoH, just spit balling along with the speculation.
Currently though, I'm still leaning towards it simply being an old part of the castle we never saw, chilling out at the edge of the property near some creature stables, as well as some caves we also never saw in the films.