Your whole argument is flawed because you cannot show that the Muratorian Canon was really composed c 170 CE. You already admitted the Muratorian Canon could have been composed as late as the 4th century but utterly failed to take the later 4th century date in your analysis.
If it were that late, then it would be pretty much useless for anything regarding the dating of the Pauline epistles.
Tim, with the best will in world - few if any of these dates, either those which you prefer, or those which
dejudge prefers, or any dates quoted in Wikipedia or in any writing from any bible scholars (or whatever they wish to call themselves), should be taken without an extremely large pinch of salt.
Most of those dates, especially all the earliest ones, are afaik what the church and theologians have tried to claim for at least the last 1000 years, and are imho quite clearly the most optimistic estimates that the faithful could put on the documents in order to claim they are as nearly as possible contemporary to the time of Jesus. In the absence of independent and proper scientifically accurate dating, which afaik is not a practical proposition for any of the supposedly earliest written fragments, it should be obvious that it is very naïve indeed of anyone to accept at face value the earliest dates given by the church, theologians, and bibles scholars.
If by some magic it was possible for us all to be transported back to those times when Jesus, Paul and the disciples were all thought to have lived, and when the first biblical writing is claimed to have been produced (gosples and letters etc.), then it should surprise nobody here to find that few if any of these people really existed at that time, and that none of the writing had been produced when it was said to have been produced. It should surprise nobody if in fact the gospels and letters etc. (inc. non-Christian writing) was almost all very much later than is now being claimed, and similarly not a surprise to find that some of these characters, and perhaps even all of them, were completely unknown by anyone at that time.
IOW - in all honesty, I think everyone here should be extremely cautious about accepting any of the numerous claimed dates for any of this writing.
On the other hand there is one very large mass of writing from that time which does seem to be both in it’s original form (unlike any of the biblical writing), and fairly accurately dated. But that is
not the biblical writing, nor is it any of the very few and extremely brief non-Christian mentions of Jesus, and that is the Dead Sea Scrolls. But significantly perhaps, although the scrolls have been carefully dated to writing produced from circa.170BC all through to about 70AD, they make no mention at all either of Jesus, or of Paul, or of anyone else described in the bible, even though the scrolls were produced by proto-Christian Jewish apocalyptic OT worshippers in almost that exact same small region around Jerusalem, and at the exact same time/date.