Sam Stephenson strikes me as the kind of guy who says things without thinking.
React is quite an non-opinionated view library that makes no prior assumptions about what you are using it for. While Facebook might have built it with the original intent of making UI composition a lot easier for their developers and UI teams, it's not a niche library. It is no more a "Facebook specific" technology than PHP is. Look at other solutions, Rails came out of 37signals, Django was created by a newspaper.
Some of the best frameworks and libraries were spun out of existing organisations/projects built to meet company needs. And look no further than Angular which came about from Google's internal Greentea team who work on a private CRM tool that Google use.
The bottom line is: it shouldn't matter who created a particular framework, tool or library. You should always pick a particular piece of technology because it meets your needs.