"I haven't run into it yet." Chouji thought for a minute about it and said, "I think I'm more upset about missing so much of my friends' lives, because they've been here a long time. That, and the fact that somebody may be hurt if I don't remember them."

Korra was being pretty open with him, so he'd give her the same. Chouji knew he'd be hurt if someone forgot about him, and the thought of doing that to someone else made him uncomfortable.