The stated made just by the Doctor, about him hunting everybody down and destroying this place…. Everybody on the scene, both players and NPCs understood that he wasn't kidding at all.
The Doctor aim was to really destroy this place.
His action.
Him releasing a plague in the city.
Him releasing those monsters in the city.
And now him transforming into the monster and committing the genocide.
There was no lie and everybody knew that.
Not only that, multiple healers that were working diligently were suddenly killed, lowering the chances of beating this "Monster" in their eyes.
The fear once again began spreading among everybody.
And now, the panic had began taking even deeper roots into everybody.
As for the Doctor? He did not cared.
He just waited few seconds after making his announcement before then starting going on the rampage again, killing anybody near him.