User blog comment:Commander VB/Mass Effect 3 story understanding/@comment-5439505-20120824230043/@comment-5337704-20120825061551

Was just my take on it. We know the keepers had to activate the controls and Saren was sent in to do it when the keepers failed. My guess is that it was a fail safe measure the original organics put into place that something physical must press the button to activate the catalyst program. Such as turning to keys to launch nukes as opposed to having a computer having that ability, but the computer must be used for targetting, physics calculation etc. Just this computer changed its targets when the keys were turned.

Hopefully, the dlc and anything in the future can add light to this subject. As this is just my take on it what was going on. Sadly I won't be getting anytime soon as it is not free, so my future opinions will be misguided if further information is revealed.