A reading of the early stages of the investigation reveals that the Brazillian authorities investigated it and concluded that it was not kerosine and this was not linked to the accident. There is nothing suspicious about BEA accepting what they were told by others and basing their search on other information. There is a little bit too much paranoia (too strong a word?) here and a subliminal assumption that the French are trying to cover up and hide flaws in their aircraft design or construction. You yourself have expressed thoughts that the investigation is being directed along certain channels. This is veering towards the suggestion that there is a conspiracy so the reference is apposite.
It may indeed be that BEA possesses a bias but it must also be understood that finding the aircraft on the sea bottom is very difficult with the information available. The latter is the more likely reason for the non-emergence of information - there just isn't any information to release. It is difficult to grasp but the undersea environment is a totally different environment and what the BEA are attempting is a first at this depth. Patience is a vital factor in this search.