MacArthur would never be at rest while in the alien system.
The original, alien systems whatever that might be, is still running them.
If she had indeed used the alien system, Margaret could have traveled to any of the planets.
"In 5 to 10 years, we'll have an alien replicating system," he said.
There, he is affected by an alien system and goes on a rampage.
"But we know nothing about how the alien system works," Geordi said.
"The walls have become part of the alien system," said Diana softly.
I agreed to your plan for the chance to learn about alien writing systems.
"I didn't know they'd gotten any of this alien system working," he remarked.
"I think he'll be an asset while we're sorting out the alien systems."