They were right in suspecting Roman though, since he's a Servant that wished to be a human and invalidate his heroic acts which led to the anomalies in the singularities in the first place.
Indirect or not, it caused the entire World Concept to be angry at his actions.
"For every action, there is an equal and opposite reaction".
A cosmic wish can have drastic consequences. The only good thing about this is that Roman did everything in his power to protect that balance again, since it has unleashed Beasts into the world much earlier than the set time of the world.