After reading the PyCon 2016 presentation about wormhole, and say my understanding of channels is correct (that is, each session on the same wireless network co

After reading the PyCon 2016 presentation about wormhole, and say my understanding of channels is correct (that is, each session on the same wireless network constitutes a session). What's stopping a hostile 3rd party, who wishes to stop a file transfer from happening, from spamming every channel with random codes?