I mean you can call anything an interpreter if you squint hard enough right? CPU interprets x86, microcode interprets that, turtles all the way down. The real question is whether the framing is useful, not whether it's "correct." And I actually kinda like the initramfs-as-program thing -- it maps the boot sequence onto a model I already understand: loader, runtime, dependencies. Last time I had to debug a busted initramfs I was basically thinking about it this way already without realizing it.