Well, it sort of depends which bunch of buttons your instructor pushed
The RAT deployes when Airsped > 100 kts AND AC Bus 1 Off AND AC Bus 2 Off, so that's normal system behaviour.
Why your AC Bus 2 failed I don't see any reason in your description. Might be a GEN 2 Fault or anything else that the ECAM weighs with a lower priority and that you would only see after clearing your multiple Bus faults and possibly other stuff 'at the top of the list'.
Regards, MAX