Taking into account the maximum possible speed of the airplane, the wreckage of the airplane must then have been within a circle with a radius of 75 km (the Circle) centred on the last known position (LKP).
Judging by the name of the blog in which issue is taken with the above statement by Jean-Paul Troadec, Director of the BEA, daylight has failed to pass by the author of the blog for 22 months. No one has ever disputed that AF447 could have traversed in a straight line 40NM from her last known position. No one knew then that the aircraft had left FL350 at or before 0210Z, though there were certainly indications that it had. Had it proceeded in a straight line in any direction, rational says that it "could" have got to the edge of that circle, but how it would have arrived at the surface is another matter.
The French best know the nature of cover-ups that happen in their society, and the culture behind them, hence this type of conspiracy theory. Best left where it was found - in cyber-space.