Call of the Haunted question

So I was watching a duel and was wondering about a small exchange that happened during.


Player A activates MST to destroy a face down S/T that Player B controls.
Player B responds by activating the targeted card.
Player B activates Call of the Haunted and summons Yubel.
Player B sends Call of the Haunted and Yubel to grave and special summons Yubel - Terror Incarnate.
Player A says that isn't allowed and ragequits.

I'm pretty sure that what player B did was right but I could be wrong.

That was completely right. Its a common move to CotH your Sangan in the same situation. Since it resolves backwards you summon Yubel, then CotH is destroyed. CotH takes Yubel with it therefore activating Yubel's effect to summon Terror.