As a potential backdoor with access to a computer with compromising the OS, how much is ME neutralized by just not using the integrated NIC and instead using a PCI-E or USB NIC?
How do you think it accesses the network? In fact, I don't think every version has network support in the first place.
It is designed for remote management of a computer. Take your best shot, do you think it has network support?
Also, it doesn't need for the computer to be powered on. One of the advertised features is remote HDD wipe, in case your laptop is stolen.