I recently had a first contact with an alien species, running into a ship of theirs. The nature of the encounter led me to believe that the ship would stick around, and so I initiated contact. Then a few days later, the ship pulled away, and disappeared, most likely leaving the system.
Still, despite the lack of conversation partners, my researchers continued to communicate with the aliens for months, finally establishing contact, and having the other empire reveal its name. Without me having any contact at all with the other empire.
Now, I don't necessarily propose that the game should figure out when there can be communication efforts, and when there can't. All I'm interested in is a way to stop the Initiate Communication action, after it has been initialized.