After close to an hour on the phone with JetBlue, going back and forth with the rep...it appears this is completely false: "JetBlue is offering $99 one-way fares to individuals with proof of a valid Spirit itinerary for the same route (or sister cities) for travel through Wednesday, May 6."
They will ONLY give you the $99 fare to fly out of FLL or SJU.
I voiced our frustration to the rep that this makes it sound like if JetBlue can get you to where you were trying to go on Spirit, they will for $99 for the next few days. Only the following paragraph indicates capped fares out of FLL or SJU. And the paragraph that DOES mention FLL and SJU does NOT say anything about $99 flights.
Misleading and confusing. Just sharing for others hoping to get that stated price. Obviously they aren't required to do anything, but they sure promised something quite different from the reality. Clearly stating what they are actually offering would be a helpful update.