When it comes to FAR/JAR 25 you won't find many that will listen to softening the rules. I thought the JAA might give Airbus a chance at proving it by analysis, but not the FAA. Turns out they both want them to prove it can be done.
I don't know where they came up with the 90 seconds. Everybody in the business knows if the airplane is on fire you got maybe 20 seconds or the fumes from toxic burning plastic will kill you where you stand.
