I'm pointing out that guilt as a signal you won't (can't) defect is made useless by having a system to remove guilt.

It's not like John is removing his own guilt for breaking Lisa's neck and taking the antidote by making himself believe that what really happened is that she actually gave it to him in his coffee and then died of poisoning. Here, guilt is removed sort of from the outside, by the society, which actually seems to make sense from the point of view of removing false (from the society's point of view) positives, while keeping all the social benefits of guilt. But, true, this mechanism can be exploited via making up imaginary friends.