The problem is not awkward syntax of PHP. Main problem is that PHP is a specialized
language. For example it does not have built-in threading. Posix threading is not
universally available for PHP. Python and Java has it's own VM-backed threading
everywhere. Java is suitable platform to build OS. PHP is not. Even web server backend
itself is rarely implemented in PHP.
http://www.artima.com/insidejvm/ed2/jvm.html
"Complete feature" language should be suitable to build OS.
Perhaps Zend VM could be "beefed up" itself to make PHP the same class as Java.
Dmitriy