Was the AMX even seriously offered to Malaysia and Indonesia? Apart from Britain having more political pull in both countries, British Aerospace was able to offer both countries offset agreements to go along with the Hawk deal. Another factor was that during that period the Hawk was probably a more mature design.
I believe in that period, the AMX been quite seriously offered to SEA. They've done several flying demo in Indonesia and if I'm not mistaken also in Malaysia. I believe Aermachi also offered offset agreement, but like you've said 'politics' with British and BAe have more 'contact's in the region win the day in the end.
What I'm getting at (at least for Indonesia), the notion that Hawk will be easier to maintain (with the excuse of the engine like the semi-official excuse) is just unfounded. Spey supporting infrastructure within Indonesia is more established than Ardour. It's simply becasue BAe with more contacts know which more 'influential' button to push in each country in the region.
Remembered we're talking about Hawk 200 series, which at that time the provenbility factor are similar with AMX (both are new design).