I don't know if the FAA regulation has changed but used to be an aircraft with an inoperative exit could be dispatched with passenger seats blocked from the inop exit half the cabin forward to the next exit and half the cabin aft to the next exit. I'm not sure if on a DC-9 or MD-80 an inop front entrance or front galley door would seating blocked from the 1st row to half way to the first overwing window exit or if only door exits figure into this rule so that only any seats aft of the rear galley door can be occupied.
Spirit must have had full loads with the aircraft out of MCO and on its flight back to the US that they preferred to replace the slide in an 8 hour delay than block seating and operate the aircraft.
A flight attendant friend had a slide pack drop out of a DC-10's 2L door into the jetbridge. It did not automatically inflate but the station was not a major one and it was late at night so a repacking repair was not possible. Half of the FC cabin forward of the door was blocked and half of the coach cabin aft to the overwing exit was unuseable. Thank God for them it was before AAdvantage elite upgrades became a thing of entitlement or all the displaced upgraders would have been rioting and arguing to delay the aircraft there for repair so they would not have to fly in a coach seat!