If my motor cortex was replaced by this robot's program, I would not conclude that I had suddenly started to only care about blue, I would conclude that I had lost control of my motor cortex.

I predict this would not happen the way you anticipate, at least for some ways to cash out 'taking control of your motor cortex'. For example, when a neurosurgeon uses a probe to stimulate a part of the motor cortex responsible for moving the arm, and eir patient's arm moves, and the neurosurgeon asks the patient why ey moved eir arm, the patient often replies something like "I had an itch", "it was uncomfortable in that position", or "What, I'm not allowed to move my arm now without getting grilled on it?"

Or in certain forms of motor cortex damage in which patients can't move their arm, they explain it by saying "I could move my arm right now, I just don't feel like it" or "That's not even my real arm, how could you expect me to move that?".

Although I won't get there in a while, part of my thesis for this sequence is that we infer our opinions from our behaviors, although it's probably more accurate to say that our behaviors feed back to the same processes that generate our opinions and can alter them. If this is true, then there are probably very subtle ways of taking control of your motor cortex that would leave your speech centers making justifications for whatever you did.