Digital security isn't a matter of simply setting things up and walking away. As hackers develop advanced tools to break into systems, security requires constant vigilance and improvements to a system that ensures that the wrong people do not gain access to the data.
This is especially relevant to filmmakers, as there is a tremendous amount of interest in the work created at the top end, such as getting new episodes of Game of Thrones or the latest Marvel film early. If you remember the Larson Studios Hack, the hacking group wasn't even specifically targetting post-production facilities; they just happened to luck into new episodes of Orange is the New Black.
Frame.io is quite publicly a place where works-in-progress (of new movies, television episodes, etc.) will be stored, and the company knows that there's a giant target on your back for hackers looking for hot content.