Because his first experience with this debate was forcing PHP on engineers who knew that would be a bad choice. No matter what you are doing, PHP isn't the right choice for it if more than 1 person will ever use or depend upon the software.
PS I've seen PHP destroy billions in value in my career. It and Brainfuck are the only 2 languages you should never use to make software for other people. Every other language has a core use it is good at. JS in the browser, Python for scripting, Java when you need good observability and 3rd party libraries, etc...
I've used PHP early in my career (around the time PHP 5 came about), and I was never a fan, but to claim that you can't built successful products with it is simply crazy: look at Facebook, Wordpress just to name the two!
And similarly, "Python for scripting" (Instagram?)... It's the effectiveness you achieve with it that is perfect for many new projects, based on language itself (dynamism, introspectiveness, readability...) and rich standard library and ecosystem.
I'd say you are not looking objectively at language choices despite the evidence being there in plain sight to counter the claims you are making.
> Because his first experience with this debate was forcing PHP on engineers who knew that would be a bad choice
Ummm... No, I think it was about forcing Perl on engineers who had been using PHP.