Perhaps slightly off topic, but I'm skeptical of the idea that two AIs having access to each other's source code is in general likely to be a particularly strong commitment mechanism. I find it much easier to imagine how this could be gamed than how it could be trustworthy.

Is it just intended as a rhetorical device to symbolize the idea of a very reliable pre-commitment signal (in which case perhaps there are better choices because it doesn't succeed at that for me, and I imagine would raise doubts for most people with much programming experience) or is it supposed to be accepted as highly likely to be a very reliable commitment signal (in which case I'd like to see the reasoning expanded upon)?