Putting aside the question of which way to implement "indifference" is better, the main reason I came up with this alternative was that I was having trouble understanding what your modified AI would do, until I realized that it would essentially act as if it believed that the measurement would come out 0 with probability 1.

Given this, I think a modified AI in your explosives example would not actually do D-H. Suppose it believes that the measurement will certainly come out 0 and therefore no explosion will occur, it would still want to avoid alarming the observer since he or she may have other ways of shutting down the AI (for example by calling someone in charge of the power plant, or pushing another button it doesn't know about). I think such an AI would still appear totally cooperative until it has manipulated humans into giving it so much power and survivability that it can survive all possible human countermeasures and win any conflict with close to certainty. The fact that it would fail to take into account the explosives in this calculation seems to make little difference to the eventual outcome.