Damien wasn't going to leave any problems unsolved.
Right now, the traitor was dead, but the Divine Order's scheming wasn't so shallow that it could end with just this.
Whether they had Giovani or not, they had the ability to use the 7th Sword as an excuse now.
Giovani had been specifically loud about his actions for that exact purpose.
Damien didn't really care about the actual act of destroying the evidence.
From the moment he decided to stand against the Divine Order, they were fated for destruction. He didn't actually need the homunculi as some sort of justification to make that a reality.
The only part that mattered was Giovani's presence.
That was where his plan hatched from.
First things first, he took Giovani's severed head and sent it into the Sanctuary along with a message.
Damian, Damien's second Avatar, took the head and the message to the main palace through the Sanctuary connection with Rose and the rest.