I do expect my service provider to filter packets for me. Not for any freedom-loving perspective, but for very practical ones:

My phone is battery powered. My cell phone link uses a lot of power when active compared to when inactive. I don't want some random ass killing my battery life by packet spamming me.

My cell phone provider charges me for data. Would that include random UDP packets spammed at my device?

The abuse potential is high enough that it concerns me. Having some sort of firewalling on the provider side seems straight up useful.

Of course not, but most consumers rely on default home router NAT configurations to at least protect them from drive by attacks on insecure devices. That's not an option in a mobile context, so I was curious at what level VZW expected their customers to be protected.