"go. i'll detonate it manually."
I find this scene so interesting. This takes place during season three's "Progeny", when the replicators mind probe the team and create scenarios for each of them, looking to "gather information from our responses", according to Rodney. In order to create scenarios however, they have to draw from the mind of the one being probed. I take this to mean that in a situation such as this, John expects Rodney to do this. He believes Rodney is the type of man to offer a coin toss on who will be the one to sacrifice himself. It really speaks to the level of regard John really has for Rodney.