I estimate, that a currently working and growing superintelligence has a probability in a range of 1/million to 1/1000. I am at least 50% confident that it is so.
The probability is already just an expression of your own uncertainty. Giving a confidence interval over the probability does not make sense.
I agree. Perhaps he means to say that his opinion is based on very little evidence and is "just a hunch".
I do think that in fitting a model to data, you can give meaningful confidence intervals for parameters of those models which correspond to probabilities (e.g. p(heads) for a particular coin flipping device). But that's not relevant here.
This thread is for discussing anything that doesn't seem to deserve its own post.
If the resulting discussion becomes impractical to continue here, it means the topic is a promising candidate for its own thread.