we all can not be sure that the creation keys are destroyed.
And about that, there are two options: 1) Use the same parameters from Zcash (as komodo did) or 2) generate our own trusted setup. The option 1 it is the most reliable and safe, because for the other option, we need to find 8-12 trusted people in the community with tech skills to be part of the process (Who would these people be?) and, delay the launch (because we will need to organize and coordinate the whole process). But the guys behind Zcash were working a lot of time to be prepare for that "ceremony" and they are working with people with the knowledge necessary for that task.