There is no confusion. If you want to use the RX rover with the RS2+ base, and they are too far apart to be on the same local network. Then you need an internet connection at both devices.
If you use a RS2+ as the base and another as a rover, then you can use LoRa instead of internet connectivity if the distance and terrain accommodate that.
I believe Bryan is just saying that when you use the RS2+, you can use your phone as a hotspot. You do not necessarily need a SIM in the RS2+. The RX will have to be connected to a smart device with internet connectivity.