you have to think about the mechanical side of things too if you just send light at a positron or any other anti particle particle it will most likely behave the same way. but if you have the entire functioning machine/anti atom or do you believe still that light will still interact in the same way. and here is a question do you believe the color wave spectrum of hydrogen and antihydrogen would both be the same if you passed the corresponding energy through a gas filled light bulb. energy by this i mean positron and electron
like when your in highschool and they show you the atomic spectrum of different gases thats different for each atom