Precisely so. At least for the Intel machines that have IME features. So all the enterprise, data-center boxes but not every laptop.

Edit: I read some more. It looks like this is going beyond what I thought and affects way more machines.

Reading http://www2.lauterbach.com/pdf/dci_intel_user.pdf, there are two ways to debug over that connector; one using the USB protocol and the other using a proprietary protocol. If this uses the latter, that device, technically, wouldn’t have to be a USB device (but of course, it could still masquerade as one)

That PDF also says your BIOS must support this kind of debugging, and, for the ‘OOB’ protocol, your hardware must support it. So, your BIOS may be configurable to make this attack impossible, and your hardware may already be protected against it.