Actually, Built-in WiFi or built-in Ethernet (at en0) will authorize MAS access. Does the broken device still show on the PCI bus? If so, you can use NullEthernet.kext + NullEthernetInjector.kext (with IOPCIPrimaryMatch that matches your vendor/device-id). If it doesn't show on the PCI bus, you would then have to go the SSDT method, and of course the only way to get your Mac to load an extra SSDT is to use a hackintosh bootloader (such as Clover). It will not affect other working devices.