I might have a community management setting, where you can choose to work as the community, and then select an icon to use as your icon for admin purposes for that community. Then, upon ticking the admin post tickybox, when an admin icon exists, it would be a) selected via keyword, and b) notification box saying something like "your admin icon for community X, keyword, has been automatically selected." And then if that person didn't want to do that, they could pick a new one by the keyword.

Though it strikes me that this could be annoying.