Only the last section applies to managed apps. The security policy section isn't limited to managed apps I'd say. Then again, it doesn't actually disable the cellular data, the device will just be marked out of compliance. You could combine both to actually restrict data usage, but that would indeed be for managed apps only.
There's another topic about it here:
https://community.meraki.com/t5/Endpoint-Management-Systems/Network-Usage-Rules-Restrict-data-usage-...