Ahh, now I remember why I was confused... I don't use ClassicStartmenu in PE either (have to admit I missed that this was about ClassicShell to begin with).
I do use it in normal Windows 8/8.1 (love it, actually), just for PE I don't really need it because StartIsBack is good enough for me and saves a bit of boot.wim space. (I mostly use [Auto-]hotkeys in PE anyway instead of a start menu, partly because that frees me from some of those awkward mousepads on laptops I'm not used to, I always accidentally tap on things I'm not supposed to).