I don't think the person you're replying to said it was not possible with PHP. Just that similarly to other languages where it's just as straightforward as the example you gave, it's not built-in.
I wasn't trying to debunk a claim that something is impossible.
No, you didn't.
What you probably meant is "run it from cron, or create an OS service that starts from init.d/systemd/whatever". Which answers the question, but isn't very impressive from a technology stack.
If they wanted something more specific, they should ask for what they really want.
I also meant long-running processes, which it sounds like is still problematic. To be fair, it doesn't sound like PHP was ever designed to be used for long-running processes, to which I guess "Fair enough", but that might make things like a job worker queue more complicated if you want to write the workers in PHP (it sounds like you'll need a dispatcher in a different language because that would be a long-running process).
Have you reported them upstream? That implies a memory safety or garbage collection bug.