There is no doubt that this is a major contradiction in doctrine. The WT has repeatedly put in print their explanation of Ezekiel's vision of the man with the secretary's inkhorn that marked on the forehead those sighing and groaning over the detestable things being done. The mark on the forehead indicating those who would be spared destruction corresponds to modern day baptism into Jehovah's organization. They have stated this unequivocally on more than one occasion, and I'm sure someone (Blondie?) who has easier access to the WT CD could pull up a multitude of citations fairly quickly.
So, if you need the mark on the forehead--supposedly a mark of identity, that everyone can see--to survive (and in Ezekiel's vision, NO ONE survived w/o it) aka public baptism--any supposed "reading of hearts" is meaningless.