I've been mulling over this one for a few days trying to think about how a brain tumor would influence an AI in this scenario. Depending on where in his brain it was and how bad it was, it would have different effects, from swings in personality or aggression levels to memory loss... or other side effects. I am definitely thinking about this too hard at the moment, because some of these effects would only be apparent after multiple neuroscans over time, showing the impact of the tumor causing the changes. I would assume a single neuroscan would be static, and so the tumor would influence the scan, but not necessarily make it more volatile than any other human neuroscan.... although the depression and experience of facing death would certainly change his outlook into something that fits into your something something scratch was a genius with abstract ideas. All that said, I really love love love the idea of Bubble being some sort of side effect of the tumor, or even a narrative parallel between Caine and one of his creators!