Oh, I see. Sure. I was reading quickly and just assumed that anyone talking about "notify when the mtime changes" actually meant, "hook into the kernel's poke-that-file's-mtime routine so it sends a notification", whether the resulting mtime was modified or not.
(In practice I'm pretty sure that the mtime *would* always be updated, though, because in linux, in-memory inodes always get nanosecond-accurate timestamps. The extra resolution gets stripped away by the filesystem driver when the metadata gets pushed out to disk, but the actual data structures used in the core kernel don't care about that.)