You could have asked me for the links, or you could look them up yourself, or you could check other threads where they are posted numerous times, but ( damn, I'm just too nice ) here they are again ...
http://www.flsenate.gov/statutes/index.cfm?mode=View%20Statutes&SubMenu=1&App_mode=Display_Statute&Search_String=&URL=CH0090/Sec408.HTM 90.408 Compromise and offers to compromise.--Evidence of an offer to compromise a claim which was disputed as to validity or amount, as well as any relevant conduct or statements made in negotiations concerning a compromise, is inadmissible to prove liability or absence of liability for the claim or its value.
http://www.jcrobbins.com/FlaRCrimP/FlaRCrimP-3.172.htm (h) Evidence. Except as otherwise provided in this rube, evidence of an offer or a plea of guilty or nolo contendere, later withdrawn, or of statements made in connection therewith, is not admissible in any civil or criminal proceeding against the person who made the plea or offer.
Both of these address admissiblity, not confidentiality.
" why do you think that ongoing plea negotiations have never been publicly revealed before under the sunshine law? "
Unless you KNOW, don't guess - Since you can't even find these simple statutes on your own, your research capability is suspect.
I've asked for any hotshot FLA lawyer lurking here if they know of any comparable request that was ever turned down. If a request is turned down, they would get an explanation of why - then we would have something to go on.