@scott In this case, ConversationContainer might define that the collection owner is expecting you to send posts to them to be added; TwitterMoment might define that the collection owner is just curating some posts they found interesting, and that they will not be considering any posts you send them.
In the absence of a “send” or “don’t send” signal, we generally assume “send” if the context resolves to a collection with an owner and that collection does indeed contain the post (“verified”)