Is there any evidence that Satoshi Nakamoto deliberately avoided adding privacy-related protocols and functionality into Bitcoin in order to avoid the ban-hammer?
It's possible but I don't think Bitcoin would be banned if there was privacy layer from the start.
There is one theory that he (or they) worked for three letter agency because he picked one encryption used in bitcoin that doesn't have a backdoor.
Satoshi was either very lucky or he had classified government information.
If so, how did he justify this decision when the very concept of sound money cannot be implemented in an environment where there is no guarantee of absolute transaction privacy?
There is no absolute transaction privacy with any transactions, even with monero.
I am sure that for Bitcoin we are going to use some interesting second layer solution that will help as achieve much higher level of privacy.