First they have to eliminate contamination from the spacecraft.
Second, the levels detected are not high enough to eliminate the possibility of life
Third, there is no reason to believe that this particular sample is representative of the entire planet.
Fourth, other experiments on the spacecraft did not detect Perchlorate.
Fifth, we don't know if life on Mars would enjoy an environment of Perchlorate. Life on Mars may not have a thyroid gland
I think the media needs to leave the scientists alone for a while so they can do their work in peace. They will let us know when their testing is done.