Voting starts in March for the Drupal Association Board election.
Currently an expiration is marked as reminded in hook_cron, immediately after the uc_roles_notify_reminder event is invoked. If reminding a user is implemented as an action, conditions can be used.
Admittedly, the use cases for needing a condition on a subscription reminder are likely very small. However, a site I'm currently working on does need and I don't see any downsides to using an action for this instead of hard-coding it in cron.