... by loading it? There are many ways to get the kernel to suck in a module you can then bang on over sysfs or whatever API it presents. You can have a local exploit in a binary with CAP_SYS_MODULE, subsystems can be fooled into passing uncooked strings to modprobe, users can be fooled into dropping junk into /etc/modprobe.d (instructions for doing so are pervasive in the embedded world and most users think this stuff is safe), etc...

This kind of chicanery is the vanilla pudding of the hacker world. It's everywhere. Suffice it to say that you're simply wrong: NO, it's never OK to argue a subsystem is safe because you personally think it can't be loaded. It 100% can be, that's the easy part.