You wrote:
“where in the text does it say this? Nowhere.”
Actually it’s right there where I quoted the text.
“Where in the text does it say Peter ever occupied such an office? Nowhere. You just made it up.”
Nope. Obtained the episcopate.
The episcopate is a office. If he obtained it rather than founded it, then it already existed.
No it didn't. George Washington was the first person to obtain the office of US President. That doesn't mean someone held it before him. Your statement makes no sense at all. The first person to hold any office, "obtained" it. The office has to be established before the first person holding it can obtain it. The text specifically says Linus was the first not Peter. The text never says Peter ever held it which it would if he had. End of Story.