It seems to be agreed that if there is a fire on board you have about 20 minutes to land or ditch the plane before it's too late. In the middle of the ocean that leaves just one option, and not a good one. Shouldn't fire suppression or fire fighting be the first course of action. Put down the list and put out the fire.
No. 20 minutes is too long. 10 minutes at best.
Fire suppression is fine, but without fire extinguishing capability, there will be more hull losses. The crew must be able to stop fire, particularly as most airplanes these days are 2 person crews.