the way i see it, Harry and Ginny would be all into bets. so, when it came to Teddy, Harry would claim that Ted would be a Seeker when he grew up. Ginny would argue of course, that he’d be a Chaser. it didn’t enter either of their Quidditch-addled minds that he wouldn’t play at all (which he doesn’t, in my head). here, Ginny is boosting her chances of being right with Harry’s attention elsewhere.