Make login attempts for deactivated users useful

We get emails from users sometimes asking for help saying they can't log in to Heartbeat, and the reason turns out to be that their account is deactivated and needs to be manually reactivated.

Would it be workable for Heartbeat to let a user with a deactivated account trying to login know that this is the case? That way people aren't confused — they forget they deactivated, and it just looks like login is broken.