The Monarchs' topic of discussion was not their lord's use of the powers that he had left behind, nor was it about the person who made him use the powers or went against his wish to remain anonymous.
The order was given to them, the Monarchs, so it was not a transgression if someone else mistakenly recognized him. Even the headmaster of the academy knew about him, but the reason THEY were not angry about it was simply because of his silence.
If the world knew about his arrival, then there was a chance that the forces that had been eyeing for his throne would resurface once again. There were already countless beings who wanted to claim supreme positions in Anovolda. There were many scavengers who wanted the throne for themselves.
There was a reason the Monarchs had protected the Academy where the supreme throne existed instead of taking out the beings that arrogantly believed themselves to be on par with their lord.