Asiana doesn't usually let non OZ *G select seats when they start holding them to minimize having to deal with the reasons you mentioned. I've rarely had an issue when I want to select an open seat(except the pet seats) when I make my reservation. I never worried when I was OZ Gold and since I'm Diamond Plus when I call to check availability before T-48, they usually give my choice with minimal hassle (no pet or bassinet seats) if they're open.

Asiana is like a lot of the *G carriers in just extending basically *G minimum benefits for non OZ elites on OZ metal.