Yep, that's what the randomness is for, and you can also add entropy by randomizing the time before the dialog starts to present he user with the "emergency connect mode instructions" which explain the disconnect/reconnect process.
Plus, 99% of the time the user is not plugging in a HID device, so the "unrecognized input device" dialog can be made ominous enough that users will realize something is very strange about that one USB stick.
Plus, 99% of the time the user is not plugging in a HID device, so the "unrecognized input device" dialog can be made ominous enough that users will realize something is very strange about that one USB stick.