Here are two additional considerations regarding the words of מר עוקבא:
אמר מר עוקבא אנא להא מלתא חלא בר חמרא לגבי אבא דאילו אבא כי הוה אכיל בשרא האידנא לא הוה אכל גבינה עד למחר עד השתא ואילו אנא בהא סעודתא הוא דלא אכילנא לסעודתא אחריתא אכילנא
1) Mar Ukva is well-known in the Talmud for his extreme piety and righteousness. See Kesubos 67b and Rashi Sanhedrin 31b ד”ה לדזיו. Why shouldn’t this statement be understood as another example of his extreme personal religiosity?
2) How could R. Chananel say-לא מצינו מי שהתיר לאכול גבינה אחר בשר בפחות מעת לעת אלא מר עוקבא? This statement is shocking. If Jews commonly waited 24 hours before dairy after eating meat wouldn’t there be some hint of it somewhere in the vast Tannaic, Amoraic or Midrashic literature? The truth is to the contrary – מר עוקבא and his father are the only sages we ever hear of who waited so long. In fact, his words are expressed in a way which indicates that he speaks of a personal private custom: .”אנא להא מלתא… ואילו אנא…” R. Chananel, himself, was surely aware of the shortcomings of his argument. He may have only said these words in order to allow for the creation of a new Rabbanite custom which would aid in segregating the Qaraites from the Rabbanites. For the sake of launching the new order of dietary and, hence, societal and communal limitations, R. Chananel devised a clever way of manipulating the brief quasi-aggadic words of Mar Ukva.
Tzvi H. Adams, “Waiting Six Hours for Dairy – A Rabbanite Response to Qaraism”, Seforim Blog (11 August 2015) [http://seforim.blogspot.com/2015/08/waiting-six-hours-for-dairy-rabbanite.html]