Other than it would break countless telecommunication laws and regulator approvals, lacks a sim card, lacks any form of application for it and the vast majority of the planet lacks LTE coverage.
This is getting into tinfoil hat territory. The mavic is a small piece of gear. Its been disassembled, broken apart, stuck on spectrum analysers. There is no chance of a fanciful technology that doesn't even exist built into it.
Apps talk to the internet when theres a connection. If there isnt one they wait and queue the requests. Its not exactly hard.
It doesn't need a sim card if it is only listening /awaiting a kill signal to tell it to lock down. Intel Anti-Theft operated on the same or lesser technology of an integrated 3G chip within the CPU. The CPU could be remotely killed even after the BIOS was reset, the harddrive wiped, and the computer never connected to any network or Internet. It just had to be powered on.
https://www.intel.com/content/dam/d...ta-with-intel-anti-theft-technology-brief.pdf