>This is because the cable is 2 sided so it can't assume polarity

Not really. The USB-C connection pinout is symmetric about a 180 degree rotation, at least as far as power connections go. It's entirely possible (and common, e.g. when using passive converters) to just put power out of it constantly. The main reason for the signaling resistors is to avoid having power presented on the pins when it's not connected, which is more about avoiding corrosion or wear due to small sparks on connection.

And to avoid having two sources (perhaps with slightly different voltages) connected together and leading to hijinks. E.g. a usb A-C cable plugged into a USB-C power supply.

By 2-sided, OP probably means that the problem is that the cable has two USB-C ends, not that the USC-c connector is symmetric.

If you have an A end and a B or C end, you can assume that the device on the A end is supplying power and the device on the B or C end is consuming power without breaking anything. The A end cannot supply power to it's device by design, so an A to C cable cannot be used to power the A device from the C device, regardless of whether the device on the C end can supply power.

But if you have two C ends, you need some way to establish which device is the supply device and which is the consuming device, because the cable can be used to connect two devices which both can supply power (e.g. a laptop and a phone).