PHP is just the first lang. It's part of the Tarsana project which is his framework for writing command line apps in any lang. To quote the Tarsana project git

PHP is just the first lang. It's part of the Tarsana project which is his framework for writing command line apps in any lang. To quote the Tarsana project git page... The PHP language was chosen simply because I wanted to rewrite my lumen-generators using this framework. Now I start to consider switching to Javascript... because javascript.