There may be an interesting connection between this example and AIs knowing each other's source code. The idea is, if one AI can unilaterally prove its source code to another without the receiver being able to credibly deny receipt of the proof, then it should change its source code to commit to an unfair agreement that favors itself, then prove this. If it succeeds in being the first to do so, the other side then has no choice but to accept. So, Freaky Fairness seems to depend on the details of the proof process in some way.