Usbc is just the connector.
Running display port graphics over usbc is no less safe than using a bigger display port connector.
USB-C always has a usb2 channel available, then 4 lanes that can be display port or thunderbolt or usb2/3 or whatever else.
This is why most android phones have options for USB including "charge only".
Usbc is just the connector.
Running display port graphics over usbc is no less safe than using a bigger display port connector.