Honestly, I don't recall - can you link for me please? Or give me one? Hand on heart, I can't recall any.
I'm reasonably sure that I at least attempted to, a few months back when you first threw the idea at me. I'll admit that I didn't come up with anything novel, but that's not the same as simply not trying.
Trouble is - as Lucifer seems to be saying - a computer simulation of a brain will NOT be an appropriate model, because it will not be "sentient" in the same way. What I believe he is saying is that even if you modelled every process of my brain in the computer, it would still not be the same as my brain, even if we could feed it exactly the same inputs.
Right now, we don't have the technology to do it, not even close. A computer simulation of a human brain, even made using the best computers available today, simply couldn't accurately model the reality. But we've only had computers for some few decades, and the first models were little more than fancy calculators. Compare those to what we have today, and consider where we might be some centuries from now; I don't think it'll always be impossible to create a virtual brain that accurately simulates a human brain, provided the virtual environment is big enough to hold it and powerful enough to run it.
Anyway, a while back I believe I brought up the idea of the structure of the brain being deterministic, but the mind itself not being deterministic in the same way. While I couldn't explain it at the time, I've thought it over some and can probably describe what I'm talking about better. The brain processes far more sensory input than the mind can deal with, even leaving aside purely subconscious info. The brain automatically filters out most of this input and prioritizes it for the mind to handle.
What keeps the mind from being locked into the brain's determinism is the other input that doesn't make it into the highest level of priorities, that the mind can still examine despite it not being deemed important enough to pay particular attention to. I think it is this that keeps the mind from being deterministic like the brain is, the fact that the mind can and does look over some of the extraneous input that would otherwise be ignored by the deterministic filtering process of the brain. A person who looks at something that isn't very important and doesn't matter to whatever they're dealing with can make an intuitive leap that they wouldn't have made normally. In other words, the future path of something isn't fixed the way its past path is, without being dependent on entropic probability (ala, random chance).