That title and article is very misleading. A) The React license is a 3 clause BSD license. https://github.com/facebook/react/blob/master/LICENSE It has absolutely no custom restrictions in it. In addition to the license for using react, they B) grant an additional patent related license (https://github.com/facebook/react/blob/master/PATENTS) such that if you use React and React "infringes" on a Facebook patent, Facebook is additionally licensing the patent to you. In this way, not only are you licensed to use the software (React), but you are licensed to use any Facebook patents that React might infringe/use. However, if you decide to sue Facebook for patent infringement (of any kind), they are going to revoke your license to their PATENTS. This only matters if the software (React) actually infringes the PATENTS. Either way, you still technically have a license (3 clause BSD) to React...but, you could be violating a Facebook patent by using it.

It's important to keep in mind that there are two different types of Intellectual Property in view here. Software licenses and patent licenses. Theoretically, you could use some software Y under the BSD license and have some third party X sue you because Y violates a patent (even though you didn't write Y and are only using it). Facebook is being generous IMO by saying both A) you can use our software and B) if we have patents that the software benefits from we also license those to you provided C) you do not sue us for patent violations, in which case we revoke B (but not A).

So, going back to the article, the license to use React would not be revoked and it has nothing to do with competing with React. It is possible that if you sued Facebook for patent infringement AND Facebook claimed that React benefited from it's patents, that Facebook could now sue you for patent infringement b/c you use React.

But, if you sue any big company for patent infringement, they are also going to look at their portfolio of patents to see what you might be infringing and will counter-sue. So, in that case, I don't feel like Facebook is really being contrary here. They are basically saying, "As long as you don't sue us for patent infringement, we promise not to sue you for any patent infringement related to our open source software (including React). By doing this, we are hoping you will take advantage of the software we have put out there in the OSS world and alleviate any patent fears you might have. However, if you choose to sue us for patent infringement, we revoke this promise, and are going to treat you just like any other Joe Schmo."

IMO, Facebook is going out of their way to make it possible for others to benefit from their OSS software by granting not only a generous software license but a related patent license as well. For the article to misconstrue this as a license revocation if you decide to "compete" with them is pretty disingenuous.