I think it is unlikely that a 10 minute block target time is the optimal time from purely an engineering perspective. I think it is most likely that the 10 minute target time is a compromise between being able to easily explain how bitcoin works, and the optimal target block time. I would imagine that explaining that blocks are found on average, once every 9.45 minutes would probably hinder the long-term adoption of bitcoin
If you want to figure out why Satoshi chose the parameters this way and if you are asking about "why 10 minutes" then you are already asking the wrong question because "10 minute" is not an existing parameter. The parameter that exists and should be investigated is "2016 blocks in 2 weeks". So the question should be what was the significance of 2016?