It does seem like if your goal was security than perhaps Rust would be a better choice.
Sure high level language can help with memory management... but plenty of CVE are because of sloppy coding, not because of low level language.
PHP bugs tend to be more exploitable, because you're doing something supported by the language.
I'm not putting any kind of weight behind that, though; I just feel that it's a bit odd for people (not specifically meaning you, just the whole thread) to criticise this purely on language choice and not put any substance behind their criticisms that actually relate to the software in question.
A high level language should reduce boilerplate and 'force' you to write concise and predictable code.
PHP does none of that especially in the context of error/exception handling.