hydrogeddon's eff vs torrential tribute

i just want to clarify if i am really correct.

scenario:

player1: had hydrogeddon and attacked player 2's BW gale and then destroys gale and activate hydrogeddon's eff which special summon another hydrogeddon from deck.
player2: then actiavate torrential tribute..

as far as i can remember you cannot activate traps like BTH or torrential during damage step right? but i was shut and cannot support my reasoning when my opp said that damage step is already over cos monster was already sent to grave and i recalled that during substep 7 which is the last substep, monster are send to grave.. so i did not argue further but still have my doubt over the matter.. ca you guys help explaining the things that are confusing?

Monster is sent to grave after being destroyed by battle at the last substep of Damage Step, so Torrential can't be activated at that time.
for more info: http://forum.duelingnetwork.com/t10413-the-7-wonders-of-the-damage-step-tcg?highlight=7+wonders