I completely agree with your points.

I didn't mean to imply that subjective time is related to the discount rate, and I tend to agree that the 'natural' discount rate and planning horizon is probably related to expected lifetime for most agents. But it's difficult to to show why this should always tend to be so.

The time dilation for extremely fast thinkers will slow down the subjective rate of return of Moore's Law type investments just as much as space expansion type investments, that's not really the core of the argument against expansion.

The second is the failure to distinguish communication latencies from communication bandwidths.

Where did I confuse these two? I discussed both. Latency subjectively increases with rate of thought and bandwidth decreases, respectively. They both contribute to divergence.