They are ambitious, but they don't see it as 'crime'; what they need is the 'Origin' from other worlds, but acquiring it doesn't require them to deal with the people in another world.
The people from another world can completely join their Project Immortality, and enjoy being Undying and Indestructible together.
Countless parallel spaces can ensure that there will be no overpopulation issues, and pseudo-infinite resources will not trigger any resource competition.
Because there's really no need; even if those in power 'monopolize' it, they will still choke on it due to the parallel nature of the world.
So, it was really a stroke of luck that they found those worlds. Joining them, becoming one of them, would make one realize how joyful it is.
But the Dusk Proxy Agent appeared. If it were just one or two, they truly wouldn't harbor malice.
Unlimited resources and being Undying and Indestructible made them quite 'indifferent'.
