Ga Tech and Tulane left the SEC to form the new Metro Conference.
There was resistance, led by LSU, that wanted a 10 team conference that might eventually play a round robin schedule.
Times have changed. There was a time when some teams would not even play their in-state rivals. In some cases the state government got involved, but for the most part it has been driven by economics, TV appeal and fan demand.
At the University level, Florida and FSU are on much friendlier terms than your posts suggests. IMO, it is silly to think that one in state school would try block admission of a peer institution if it benefits both schools and the conference as a whole.
However it is not likely FSU will ever get into the SEC because Bobby Bowden chose the ACC over the SEC when both conferences "offered" admission in '91. Bowden burned a number of SEC bridges during that time especially with the new SEC Commissioner Roy Kramer. Bowden basically told Kramer and the SEC to go do something to themselves that TOS does not permit me to type.
There are still some bad feelings between the SEC and FSU. Since joining the ACC, FSU has had exactly 0 scheduled home/away games with any SEC school not named Florida, in spite of the best efforts of both CBS and ESPN.
In the 10 years prior to 1992, FSU regularly played SEC teams, especially Auburn and LSU. Also the regular season games with USCe came to an end after they joined competing conferences.