For what it’s worth, Chia recently enabled these sorts of reverse timelocks; see CHIP 14 (or the proposal PR or the activation PR). The announcement mostly describes it as being useful for decentralised exchanges rather than payment channels per se:
Expanding the Offers primitive, we’re proposing a CHIP, “Assert Before,” a soft fork to add new Chialisp conditions that enable Offers to expire. We expect this to dramatically improve the liquidity and depth of digital asset trading on Chia DEXs; while providing a superior model to centralized exchanges (CEX) and automated market makers.
I couldn’t find much in the way of background technical discussion; mostly I think they decided that the complexity around reorgs (small/accidental reorgs likely won’t hit a transaction block anyway?) and mempool management (mostly empty anyway?) just wasn’t that big of a deal. So not sure there’s anything much to be learnt from there…