Forum:Ritual Query Regarding Unnecessary Tributing of Djinns of Rituals

An issue came up while playing an online game. Here's the scenario;

I have 2000 life points, no monsters and a face-up Gravity Bind; it's my opponent's turn. He has three cards in his hand. My opponent plays Ritual of Destruction, intending to summon Garlandorf, King of Destruction from his hand. He sends a second Garlandolf from his hand to the graveyard to pay for it; however, he removes a Djinn Disserere of Rituals from his graveyard to give Garlandolf immunity to traps, overruling my face-up Gravity Bind. He then attacks for game. I questioned whether the move was legal, but I was ensured that it was. I question this decision and therefore, I am now here.

So. Was his play legal, or would he be unable to remove Disserere from play as a tribute for the ritual?