I have tried to imagine a superior civilization that would control the internal structure of a collapsing star to keep the interior tunnel stable.

Do they have artifacts of the superior civilization they say is at the center of the Galaxy?

Charmian says that contact with "superior" civilizations is something you don't wish on your worst enemy.

From what you say, he must have come from a vastly superior civilization.

Such a ship would imply a vastly superior civilization, at least in a technical sense.

That it cannot survive an encounter with a technologically superior civilization.

Even when the superior civilization wishes only to assist.

We may find it difficult to understand such wisdom, but that is exactly why they are the superior civilization.

We offered them aid, companionship, trade, contact with a superior civilization.

To a civilization that thought the way this one apparently did, the idea of meeting another equally advanced or superior civilization would have been terrifying.