Thanks for your reply! That makes sense.

Regarding your first paragraph: is this the scenario you describe in "A potential problem, solved" on the Github page? Am I correct in saying that if Alice initiates a closure in state X-1, she will not be punished (the (counterparty && sender) spending condition mentioned on Github is used, as the revocation secret is not yet shared), whereas if she closes the channel in an earlier state, she will be punished (as the revocation secret for that earlier state is known now)?

Cool idea! Maybe I am missing something, but when setting up the Hedgehog channel, what stops Bob from just holding Alice's funds in the 2-of-2 multisig hostage, by not cosigning the transactions proposed by Alice? And potentially blackmailing Alice to cosign only if she sends over more of her funds in the channel?