How about this as a strategy?

1. I'll make the regex an attribute of some kind so that it's easier to override through the end-user's environment.
2. I'll add another attribute to enable zapping the disks that match the regex, regardless of what's on them. Enabling forced zap is useful in testing environments and also useful when re-purposing disks.
3. If the forced zap is not enabled, then a check will be done for whether the disk has anything on it before preparing it. If it does, this discovery will reflect in the log as a WARN.