The proposal includes an upfront payment made by the sender that can be made somewhat large without negative impact on honest nodes. However, if an attacker is on the other end of the uncontrolled spam payment, they could still collect forward payments. This kind of attack, known as short-lived controlled spam, would need to be brought under control, possibly through penalization. The proposed system includes properties such as HTLC amount, forward up-front payment, backward up-front payment, and grace periods. Routing nodes would forward payments with lower forward up-front payments and higher backward up-front payments to deter attackers. Overall, the proposal appears feasible.