I think the key in your scenario is that a person already has settled substantive beliefs that aren't tilted toward any particular candidate. As long as someone really feels like they can justify their pox-on-both-houses apathy on nuanced policy grounds, that's perfectly fine.

I'm talking about something slightly but importantly different. I'm talking about someone who isn't already settled on those questions, but nevertheless feels that their sense of indignation at having their dinner interrupted by a phone call is more important than who the next supreme court justice is.

There's two failures there- one in the chosen form of interaction, which has no possibility of creating a real connection to a person and doesn't seem to come from a place of caring what they think. That's real and needs to be taken seriously.

But then you have the second failure: of letting this personal desire for validation of one's autonomy become the whole of one's political perspective, at the expense of any consideration of policy outcomes that will affect hundreds of millions of other people.