Good to see you back on the forum. Yes you can get the MAC address of Intel AMT using the SDK. Please use the NetworkAdministration.exe in WindowsIntel AMT SDKBin folder. Try to use the API as shown below:
NetworkAdministration.exe -A -verbose -user admin -pass PASSWORD http://hostname:16992/NetworkAdministrationService
Tha above command should list all of the network parameters. Look for the sample code for this in the samples folder. Hope this helps.
In the new version of Intel AMT Commander, I added a button to get the network interface information and noticed that the MAC address it's not avaialble on AMT 2.1, just 2.5 and above. You can still get other network information on 2.1 computers like the Intel AMT IP address, subnet, gateway, DHCP mode, etc.
Ylian (Intel AMT Blog)