Card Rulings:Defragmighte Dragon

"When this card declares an attack, destroy all face-down Spell and Trap Cards on the field. Card effects cannot be activated in response to this effect's activation."
Not only does this mean that Card Effects cannot be activated in response to the Spell and Trap Cards being destroyed, Card Effects cannot be activated in response to DD's attack.

"When this card is destroyed by a card effect, you can remove from play 5 Rock-Type monsters from your Graveyard to Special Summon this card."
This effect can only be activated in response to it being destroyed, and the effect cannot be activated later on in the duel.

"This card is also treated as a Rock-Type monster."
Although this card is also a Dragon-Type monster, it is NOT treated as a non-Rock Type monster.