Clear data before import and not after export

Lets say I want app to have "Internet" permission but I dont want to give it "Contact" list permission.

Now I plan to upgrade ROM.

I export XPrivacy data, put phone in flight mode, clear XPrivacy permission. Upgrade ROM, Enable Xpose. Then boot to new ROM.

Now since permissions are clear, the app can fetch my contact information immediately after boot and store in its memory.

Now I import permissions (internet is allowed). And turn off flight mode and wifi on. So now app can send the data fetched before import to its server.

So its better to clear just before import (even if UID changes its still safe). And soon after import it will anyway be back to proper expected permissions.