Food for thought from America Magazine on this event.

"Francis revealed today [note article date was 22 Oct 17] that the cardinal had sent him a letter on Sept. 30, 2017, in which Sarah thanked the pope for 'Magnum Principium' and provided him with his commentary, which the cardinal had already sent for publication in L’Homme Nouveau the next day."

Later, regarding Francis' 15 Oct letter to Sarah:  "Pope Francis asked him explicitly in his letter 'to provide for the dissemination of my reply to the same sites' on which Sarah’s commentary was originally published. He also asked Sarah to send his letter 'to all Episcopal Conferences' and to 'the members and consultors' of the congregation that he heads."

While I may wish Francis had a chance to handle this quietly and internally, I don't think Sarah gave him that chance.  Sarah's actions were deliberately provocative.  Francis made sure no one involved remained confused about CDW's limited role in liturgical translations.