Uninstalling module retains user-specific theme, variables

Issue Summary

[Drupal 6.12]
I feel silly because I was going crazy trying to figure out why my theme was "stuck". Turning off this module leaves the user-specific theme in the 'users' table.

I'm pretty sure the column for 'theme' was already there, and I'm guessing there are other ways to set the theme for each user, so would it be a good idea to clear the themes set by the module?

I think the "proper" way to do this would be to remember what theme each user had when switchtheme was enabled, and return to that state when the module is uninstalled. This would necessitate another table (?), one call during uninstall, and either one call during install (bulk for all users) or one call for each user the first time they change the theme.

Also, if there were going to be an uninstall for this module, it should clear out the other variables set by the module.

*could be considered a bug?*