They aren’t saying it is difficult without giving away trade secrets, they are saying it is difficult because the software has dependencies on internal services

They aren’t saying it is difficult without giving away trade secrets, they are saying it is difficult because the software has dependencies on internal services, which themselves have dependencies on other internal services. Basically, in order to run it you need to also run the entirety of Google’s tech stack. This doesn’t work for an open source project. They aren’t worried about ‘giving away the idea’, they just don’t have an easy technical way to open source just the one component.