> If someone is showing you a tv show it seems extremely rude to me to not look at the show as a way of passively showing disinterest vs just saying it’s not for you; no?

Those aren't your only two options. There are almost infinite ways to communicate.

Like what? What’s a polite, non verbal way to show disinterest that is not available to you when in VR?

I don't understand your question. That's how people express emotion, mostly. I'll trust you are not being argumentative:

Facial expression - eyes (the muscles around them), mouth (smile, blank, frown, etc) - posture, legs, arms, etc etc etc. You can look disinterested, you can look like it's the best thing ever, or any other human emotion.