The repository included the private portion of the platform key in encrypted form. The encrypted file, however, was protected by a four-character password, a decision that made it trivial for Binarly, and anyone else with even a passing curiosity, to crack the passcode and retrieve the corresponding plain text.
It's like installing a top-of-the-line alarm system for your house with camera, motion detector, alarm, and immobilizing gas, then leaving the unlock password on a PostIt under the welcome mat.