Partially correct, but not necessarily true. Speaking extremely high level, the model is currently trained to fill in the blank space with something like the most probable options per pixels, based on the training set data. However, it is conceivable that it could be trained to also, say, insert an object into a scene, based on other characteristics found in the scene. Inotherwords, it could be trained to maximize a joint goal, where the second goal involved generating an object.
