Currently the impostors system follows mostly the performance ranking system and is automatic.

But some impostors really don't look nice at closeups or when they move,

so it would be nice to have an option to force show their fallback instead.

For example the same way that the current "Show Avatar" works :

the menu could be extended to let the user choose between Show Avatar / Show Fallback / Show impostor.

So that if you don't like the impostor you can still switch to their fallback or their original avatar on a per user basis, or force their impostor instead of the robot in case you are currently hiding the avatar, and so on.

(as in a way the current "Hide avatar" option is kinda already a "Show robot" option)