Not really an U-turn, still an attack on the Open Source Definition
Adam Wolff makes some very troubling statements:
(1) "Next week, we are going to relicense our open source projects React, Jest, Flow, and Immutable.js under the MIT license."
(2) "This shift naturally raises questions about the rest of Facebook's open source projects. Many of our popular projects will keep the BSD + Patents license for now."
Both of these statements clearly indicate Facebook considers their Patents license clause to still be part of an Open Source license. This claim throws away the community established Open Source Definition as stated by the non-profit Open Source Initiative by replaces it with Facebook own for-profit definition of "open source." Their corrupted BSD license is not an OSI approved license and therefore none of the projects covered by it is Open Source. There is no such thing as "rest of Facebook's open source projects." There is simply the rest of Facebook's projects which are source code available under non-open source terms.
While Adam Wolff's announcement that React, Jest, Flow and Immutable.js will now finally be put under a true open source license is a welcome change, the fact he feels Facebook can unilaterally redefine them as always having been open source is a major problem.