Yup. From the start of the ruling:
"We transferred the case to this court on our own motion. [FN3] We now conclude that the answer to the reported question is, "Yes, where the defendant's compelled decryption would not communicate facts of a testimonial nature to the Commonwealth beyond what the defendant already had admitted to investigators.""
So: don't admit the disks are yours, don't admit you know they're encrypted, don't admit you can decrypt them. (Of course, "don't say anything at all", the old standby, covers all of those, thus once more proving its value.)