As explained by Kimathia, this clause has always existed, but no one, even after years of inactivity, has ever found their characters deleted.
Which doesn't guarantee that it cannot happen in the future, but except if there was a serious need for that, I can't see why they would delete unsubed accounts' characters, seeing how so many old players, myself included, came back after long breaks, and might be dissuaded to do so if their toon was deleted.
Anyway, they probably just cleaned their databased with the recent merge, since any unsubed account's characters has been deleted then.
Which doesn't guarantee that it cannot happen in the future, but except if there was a serious need for that, I can't see why they would delete unsubed accounts' characters, seeing how so many old players, myself included, came back after long breaks, and might be dissuaded to do so if their toon was deleted.
Anyway, they probably just cleaned their databased with the recent merge, since any unsubed account's characters has been deleted then.