I think mainfrog has a very good point. However 4 miles out its easier to talk to atc than cabin crew, and the last thing you want to do at that stage in the game is to complicate things when the engine has gone pop. The workload has already gone through the roof.
In practically all engine fires the main thing is to get the aircraft on the ground, and at no position are you better placed to do this than at 4 miles final and configured. So what if you've got a touch more flap, use some flying skills and stick a bit more power on the other engine, try and get the fire out, but get it on the ground!
I certainly think its important to canvas opinions from all sources where there is doubt about the problem, but time was a factor here. In my opinon the bright red lights and the fire bell would be enough at this point in time. Unless you're of the community who would question this, believing the indication to be caused by 'a major bleed leak'... Where's the indication to tell you that it wasn't!?!