Okay, I had understood you to mean that enforcing an FTL was already sufficient to enforce a PTL, but as you write, it would just cause honest miners to adhere to a PTL in effect.
I gather now that your suggestion would be to
- Enforce a 2h FTL
- Enforce that no block may be dated older than 2h before any of its predecessors’ timestamps
I see how that would prevent both the timewarp attack and your attack, and would be simpler than the MTP rule, and would lead to a similar outcome as the current rules for honest participants.