If legit but this strikes me like the photo was taken in the 1980's. I would imagine they would have tried to promote it at the Disney Parks back then.
That would make sense. If the Black Cauldron really had the production budget that was reported, Disney is going to do their best to at least try to promote it so more go see. it.
Sadly because the film was considered a flop, we are not going to see that much of it. They should just put it out on Disney+, I mean how hard is that to do?