However, with AliceSecret1 in TX2, if Alice ever broadcasts and takes the bounty, Bob can confiscate TX2:0. AliceSecret2 is courtesy of Alice, so Bob can get the bounty back. It's unsafe for Bob to use the channel before he can reclaim the bounty with some confirmation. Tier Nolan mentioned that the nLocktime for TX2 is costless and prevents fast initial channel close. Once an unchanged version of TX1 is in the blockchain, all further updates of the channel can exclude the nLocktime. The bounty is set up so that Alice can unlock it once the channel is established as a courtesy.