An interesting aside in Ignatius' writings, he specifically states that Peter could not speak the language and had to use Mark as an interpreter. I sincerely doubt Peter would have felt comfortable living 25 years in a pagan culture, unable to speak the language, and finding their food repulsive while friends and family awaited him back in Jerusalem. Paul, on the other hand was fluent in multiple languages and felt entirely at home in many cultures. Paul also enjoyed traveling while Peter did not. When the Christians were scattered, the apostles stayed in Jerusalem. Ignatius doesn't specific how long Peter was in Rome but, IF he was correct (keep in mind he was going on hearsay), then I think it was a brief visit.
I believe your analysis is completely on target Uncle Chip.
Paul was also a Roman citizen and Peter was not. And after Claudius issued his decree for all Jews to leave Rome, Peter would not have been able to even get into Rome [unless he was there as an illegal alien]. I would really like to know just exactly what Ignatius did write about Peter in Rome. The most that I can find that he ever wrote was the following often erroneously cited as evidence of such in his Epistle to the Romans:
"I do not as Peter and Paul, issue commandments to you. They were Apostles"
This is often cited by the magisterium as proof of that 25 year Petrine Bishopric but I don't see it. I'm trying hard to torture this quote and squeeze out of it all I can but it will tell me no more than what it already has. I am trying to decide whether to include it in my treatise but honest scholarship might force me to set it aside.
Ignatius is simply saying that he does not issue commandments to you Romans like Peter and Paul did at the Council of Jerusalem. Doesn't that sound like what he means by these words. Furthermore Ignatius identifies Peter [and Paul] here as "Apostles" not Bishops.
So if anyone can find anything in Ignatius's writings about Peter in Rome, please post it to me anytime and I will include it in my treatise. And there might be some here who are putting together a treatise AGAINST Peter being in Rome. So they might be interested in things that testify against that 25 year Petrine Bishopric --- and maybe even this quote above for their treatise.