From my experience, it's almost impossible (or extremely impractical) to book a QF marketed EK flight unless flying Australia to Dubai or beyond. The opposite direction is only able to be booked as an inbound flight. This became the case not long after QF stopped flying to Dubai. There may be some obscure way of making it work but the price will be outrageous.

I'm assuming your journey doesn't start in Australia as DXB would be a long detour to get to Thailand.