Well fishy..lets take an example...Singapore, twenty miles west, six thousand descending, all the radar screen shows red (general rain showers in the vicinity) from the aeroplane to the runway.
What are you going to do? Hold for the rain to move away (could take hours, how much fuel do you have....all good questions, and I have been in this situation many times there...the answer is use contour to deviate 'round the larger buildups and accept the generally rough ride. Weather is part and parcel of the airline pilots job, like it or not.
OTOH, for a pilot to go off an a tangent, without advising ATC before hand.....is NOT a good idea, for him OR the other aircraft in the TMA.
You do your best...and use the experience at hand. That is what you are paid the big bucks for.
