Interesting and relevant article on the action taken against Six Feet Under in similar circumstances. In short, if you cannot prove direct copying, the test of 'access' plus 'substantial similarity' is a very tough one. In the case of Axanar, for example, access was easily accepted by all, and 'substantial similarity' was, to be frank, obvious and easy to prove. Element after element was directly lifted wholesale from copyrighted work without any attempt to disguise it.
This case is far from the same scenario. Even access would be hard to prove given that it has never been distributed.
This case is far from the same scenario. Even access would be hard to prove given that it has never been distributed.