No, it is worst, because even if he has other cards in hand, and even if a can cast the creature, he is locked.
As you can fill his hand each turn, and he will only be able to cast the remaining cards and the creatures you give to him.
So it happens as soon your opponent has a nightmare on top of his deck, there is a creature in play and you have a mindgate
and enough quanta to use the gate and nightmare.
Of course if he can cast the big dragons you give to him each turn, it could be a nice lock for your opponent, but it's still a lock.