This couple has been civilly married for 19 years and have two children. It’s not very likely they are living as brother and sister.
Their children were conceived long time ago. Currently they would have to live without sin for the Pope to say they can receive the Holy Communion.
It does make more sense, since the most recent clarification from the Vatican said that none of the Catholic teachings have changed regarding divorce and civil remarriage.
It's all a media spin to confuse the populace (as evidenced by a number posts in here) and to make the Pope look like a freak.