If you go to their store page, you'll see their side of the story. Basically they say that the hack clients were sideloaded / modified versions. Which if you think about it, might be the way the police cracked the network.

"Sky ECC platform remains secure and our authorized devices have not been hacked.

There have been recent news articles that claim Sky ECC has been hacked and is involved in criminal activity. This information is not accurate. We have looked into these claims and discovered that a small group of individuals illegally created and distributed an unauthorized version of Sky ECC which they modified and side-loaded onto unsecure devices. Security features that come standard with the Sky ECC phones were eliminated in these bogus devices. ..." [0]

[0] https://store.skyecc.com/