In the griefing attack of today, R can lock the funds of F for a little less than the time limit imposed. The Mitigating Reverse Griefing technique has added more steps, which means that there are more places where a participant can stop responding after some step in the protocol, and thus add even more attack surface. It returns the original griefing attack, and it is a principle of protocol design that protecting against one attack could open you up to the opposite of that attack.