Board Thread:WARNING ALL USERS False Info\Spoilers/@comment-24224179-20140307044334/@comment-13188083-20140307050446

It's a word play. It means as you said "empty" but it's also referring to the fact that they want to remove the Void from Stiles.

de-
a prefix occurring in loanwords from Latin ( decide  ); also used to indicate privation, removal, and separation ( dehumidify  ), negation ( demerit; derange  ), descent ( degrade; deduce  ), reversal ( detract  ), intensity ( decompound  ).