OSU would definately prevent that in a manner similar to Florida blocking FSU and Miami from joining the SEC.
That probably hurt the other Ohio teams back when the Big Ten was the only option.
Now the Pac 12 is the only P5 Conference that would be completely out of the question from a geographic standpoint.
Cincy openly petitioned to join the Big 12, and the Big 12 said "thanks, but no thanks."
The other three already have 14 teams.
Politics might be keeping BYU out of the P5, but not Cincinnati.