That is quite worrying. Is there a way to prevent the leak?
My understanding was that the keys were only needed to initiate the process and were then supposed to have been destroyed. They were created by six different people, including Peter Todd, a BTC dev who had a skeptical attitude towards Zcash (but was willing to participate when asked by the Zcash team, as it helps to have such an outsider as one of the six.)
There's no way to utterly disprove the idea that someone pulled some stunt with the keys at some point at the point of launch, but the publicized process for creating the keys and deploying them sounded pretty robust and appropriately paranoid.
If anyone has more concrete info I appreciate correction, I'm just going by what I recall from 5-6 months ago.