i think this comment misunderstands what frankenphp and the foundation are.

• its supports php because it is php. its built on top by loading it as a library. it doesnt implement the language so is not and does not want to be a replacement.
• the foundation doesn't choose where the language goes. They support development in various ways but language design goes through an rfc process influenced by lots of people.
• frankenphp does come up in devel mailing list discussions. i think its largely thought it being an external project is a stregth but also closely part of the project.

FrankenPHP is now part of the PHP Foundation's work though...