An evil character can have as many motivations as a good character, even noble ones, the only difference is in how they achieve an objective.
They will have less compunctions about doing unsavory or even violent things and they are not going to waste time helping Sally find her lost Bunny rabbit.
A psychotic character is going to have unstable motivations, which could swing wildly all over the place, but we are talking CE with the added mental health issue as well.
A character aligned to an evil Cult or God will have at their core the need to belong and feel safe. They will do evil things for the Cult because their fear of being alone/unsafe will compel them to.
In the case we are in we are faced with both a choice and a motivation.
We can choose to 1) control the Tadpole or 2) we can choose to rid ourselves of it.
Evil will choose the first option as often as the second, and good will almost entirely stick to the second option, and I don't know why they would choose the first.
Again, the theory holds that Evil has the greater range and flexibility.
