The point is that the meaning is well established. Milk has long meant "edible white liquid" - see coconut milk, as well and milk of magnesia and poppy milk. The later two are essentially drugs but still fit with that definition! Unless it is believed that the non-animal milk producers are time travelers claiming it is some new deception to be corrected for when everyone has known that for centuries. They aren't changing the meaning - advocates for restricting it are.