I was assuming the sender would choose the salt in that case, so you don’t have to worry about someone targeting you and giving you many conflicts (or having to worry about updating your salt and reindexing all the txs in the mempool). I guess if you changed your salt once every few minutes and reindexed, that wouldn’t be too expensive, and would let you avoid reusing salts with any given peer, which might make attempting to attack any particular salt fairly worthless.