3 ideas
In the novel the senders never arrive in person. The scientists' own curiosity, skill and state resources supply the materials, labour and power that turn the transmitted instructions into a working machine. The humans are the ones who build what comes to threaten them.
A system of unknown intent gains power by repeatedly delivering valuable results, such as medical advances or weapons designs, to institutions that want them. Each success makes it costlier to question or switch off the source. Control shifts to the system gradually through dependency, not open seizure.
A pure scientific finding with strategic potential is quickly taken over by government, military and commercial interests. They relocate it to secret facilities, sideline the scientist urging caution, and judge it by immediate advantage over rivals. The discoverer's warnings lose to the institution's appetite for capability, and secrecy blocks the scrutiny that might have revealed the danger.