He had only a few moments to send a message into the past. He couldn't survive the trip through the wormhole, and he didn't know that anyone would be on the other side to receive what he sent through, but he had one chance to send a short message, for good or ill.
He thought about the impact his message could have. What tragic events could he prevent, and how could he steer the course of history?
He considered his own life and what he would change. In the end, he only sent two words through the portal.
"THANK YOU."
Happy Thanksgiving!