I enterpret Iwai wanting to go the same school with Omiya is probably not because of yuri. but because the rest of their friend group has their own partner whether they're possible love interest or not( even though all of the duo we have so far genuinely give possible couple vibes, especially the new ones)
I think that's why Iwai wanting to be side by side with Omiya, she's the only one that doesn't have any duo of her own, so Iwai would be more happy to be with a friend that needs her company