The choice is of course political, and it may well be Rafale which (by the way) is a very good fighter, although it is terribly expensive. The evaluation should hopefully be done in a professional manner, although one never knows -- I guess that, if the evaluation produces a result that you like, you consider it a good and professional evaluation; if it does not, it's probably because it is political, etc...
It is not clear to me what you are trying to say; Are you saying that the 30,000 page report is a political statement?
Also, what do you know about the requirements of the FAB? It seems you claim you know those requirements better than the evaluation committee since you seem to indicate that they need a Ferrari not a Volvo...
I find that rather funny.
Look at statistics, look at how many single-engine F-16 and Mirage have been sold in the world, compare that to the number of twin-engine fighters that have been sold in the world. Without knowing the details of the Brazilian requirements, but just using historical data and simple statistics, the probability that a single-engine fighter is preferred in any competition is higher than a twin-engine. And as said before, the Rafale is also an expensive twin-engine (more so than the SH).
Would you care to give some sources of the FAB requirements since you seem to know them pretty well?