They are certain that the first sage would be angry about what they have done. But currently, the Kickstarter is an isolated space and time. In a normal situation, the first sage shouldn't know that they are responsible for making a world-ender come into contact with his supreme law.
This is an expected reaction since they are too weak to come into contact with one and shouldn't be crazy enough to mess with a world-ender. The first sage shouldn't blame them for it because of this. Even if he finds out somehow and blames them for it, Ideally, the first sage shouldn't be able to do anything about it and ideally, the first sage shouldn't try to do anything about it.
The first sage should be safe because the isolation of space and time is preventing the escape of the world-ender. But if the first sage decides that he is willing to have his world destroyed in exchange for bringing down Legion, then the isolation of the Kickstarter will be tested by the might of a world god.
