Yes, I agree with that. I recall the analogy of taking the brain's neurons and connections, magnifying it in size to cover an entire block in a large city, and the immense density of connections would still be too large to make any meaningful observations even given our current technology.

I don't believe any optimism is required, though, to claim that we can be simulated. Unless we exist outside of the realm of physical things, that much is given. It's impossible to make good predictions about the future where the sample size is n = 0.