> that block would be rejected by every node online at that moment.
you are saying it yourself here "at that moment".
what rejecting a change proposed by the kaspa devs looks like? what happens if miners support the change but you don't.
also nothing blindly trusts PoW.
but with default kaspa node if software rules changed at some point for a while you would have no idea because you dont replay those txs. you just trust what the network tells you the utxo is.
if a chain has 2x of pow of your current chain in bitcoin, but has a single tx that doesn't fit into your ruleset, you wouldn't pick that chain.
but with kaspa you have no idea that happened. you either have to always online to catch it, or run and verify every tx from the genesis.
you can only prove everyone on the network agreed that valid utxo set looked like "this" at some point.
no matter how many tricks, ideas you have not to verify txs one by one for real. none is actual verification of the tx.
that's trust, not verification.
you cannot meaningfully prove anything about the past.
have fun complying to another hard-fork that activates "smoothly"
