Question regarding t0 and t1
My understanding of block.timestamp is that the value is set by the miner and that its drift regarding the time is not clearly defined.

Therefore wouldn't it be wise to specify a block height as a replacement or an addendum to the timestamps t0 and t1 so the risk of coordinated attacks on the protocol?

Such attacks could be Bob and a cooperating miner moving block.timestamp past t0 to enable a Claim even though Ready was not called by Alice or Alice cooperating with a miner to move block.timestamp past t1 so Refund can be claimed while a Claim is in the mempool and therefore Alice can retrieve her ETH while having access to s_b to get the XMR too.