The pieces have been thrown out there to lead us to believe that Widmore wants to throw desmond down the light well. He performed the experiment that proved Desmond can tolerate large amount of electromagnetism. The end result besides him surviving was he mentally had recollection of both the sideflash. WHEN he's thrown into the well of electromagnetism what could happen? We saw what will happen to an ordinary human, what will happen to Desmond?