file_load() in media.module overrides themekey setting

I am having a problem with the media modules filter. I am using media-7.x-1.2. On line 174 of includes/media.filter.inc, there is a call to file_load():

$file = file_load($tag_info['fid']);

This call somehow initiates the theme engine, which invalidates the theme switching the themekey. Can you think of any workarounds? I tried digging into file_load, but it uses an entity_load, so it seems like this is buried deep in Drupal core's internals.

Thanks!