I point out that Cardinal Walter Kasper has been running to the press on the issues about which they inquired for two decades, that there have been multiple previous inquiries to the Holy Father privately, that the Holy Father made a comment to the Argentinian episcopal conference that was more than slightly confusing, that there is considerable dissension in the Catholic media and discussion groups about what in the world the Holy Father means to say, and that various bishops have made diametrically opposed statements on the question asked.

The content cannot by any reasonable construction be termed "open defiance". It is a good question, respectfully submitted, the answering of which is clearly in the Holy Father's job description, and at best your construction as to why the Holy Father has been silent is speculation.