Forum:Union vs Gemini trap hole.

Yesterday my german friend and i got into an argument over the rulings of Union cards (in particular Mechina Gearframe) against Gemini trap hole card

This is what happened: On the field he had a gemini monster and the Gemini trap hole set. I had a machina sniper and a machina fortress + gearframe attached via union (good combo at that), i then attacked his gemini(treated as an effect) monster with my fortress and he activated Gemini trap hole reading: "Activate only when a Gemini Monster that is treated as an Effect Monster is destroyed by battle. Destroy all monsters your opponent controls."

He argued that my mechina sniper and gearframe + fortress would be destroyed but the gearframe clearly states: "If the equipped monster would be destroyed, destroy this card instead". He emphasized the "Destroy ALL monsters your opponent CONTROLS". so we argued for a while and searched the internet but i just gave up all 3 cards to the graveyard so we could continue the duel and i still won any way :p

Just want to clear this up.

Thanks