Up until this point I'd been willing to give the search management the benefit of the doubt but this latest fiasco is pretty much proof that they're muppets
Sorry, but I disagree. The whole lesson of eventually finding AF447 was the "Bayesian" theory.
Each piece of information is evaluated, given a probability and move on from there. As with AF447, the "LKP" is often accurate, even if other info suggests otherwise. The Inmarsat info would have been evaluated, given a probability, but not straight away, enough weight to call off the other search areas.
There is also some practicality. The assets available cannot all be switched to/from areas at will.
I think it is also clear the search teams / location have been a day or 2 ahead of what we are told the "latest" info is i.e. as info comes in, someone is evaluating and actioning it. Just not the chap in front of the cameras
Edit: reading a bit more on it, you concentrate on where you are most likely to find it. That is not the same as where you think it most likely is! The original search was in shallow water, and a small area... so if it was there, the P of finding it is much higher than the deep / enormous South Indian Ocean. The former search has now stopped since not only is the P higher it is in the Indian Ocean (or the N), but since the South China Sea has been so extensively searched, the P of now finding it there goes down. Or something like that!