Hi mP,
"The argument that P didn't mention facts about J makes no sense. He often gives other mundane facts that we can assume they already knew. He repeats personal details about himself which they already knew. The easier to believe or ponder fact is that P didn't know our J. If you read the text J exists on a different spiritual plane. P's Judaism is different from that of the apostles."
Alas, we can't go back in time and interview Paul or Jesus. Probably the best we can do is get a sense or feeling about what Paul knew about Jesus and what he didn't based on the material we have. As per the record in Acts, Paul, in fact did not know Jesus personally, so I would argue that favors the idea he wouldn't reflect on specific details from the historical life of Jesus.
Consider Paul's words a Colossians 2: " See to it that no one takes you captive through hollow and deceptive philosophy, which depends on human tradition and the elemental spiritual forces [ a ] of this world rather than on Christ. "
I think the mention of "philosophy" is key to understanding Paul. The Roman world of his day, was influenced by Greek philosophy. Paul even quotes from the Stoic Philosopher Aratus at Acts 17:28 " For we are also His offspring ." Paul viewed knowledge about the Christ as the answer to competing philosophy of his day. Also notice when Paul make these sort of arguments his stress on "Christ" rather than "Jesus."
Even many modern preachers of Christianity talk very little about the historical details of Jesus life.
In summary my argument is, given that Paul did not know Jesus personally and his style was to focus on philosophical aspects of belief, we should not expect him to comment on many historical details of Jesus life. Even so, there is at least one case of historical reflection. 1 Corinthians 11:23-26, reflects on the last supper event.
Cheers,
-Randy