Bad Sport

That's what you get for signing up for a long game on the internet with a stranger.

You are on a computer, so just read something, or play another game while you wait

Well yes this is literally true, but not necessarily deserved - why do people think that players who want to play long games deserve to get jerked around by inconsiderate clods? 

People don't deserve to get run over but what would they expect if they ran out into freeway traffic?

Until chess.com provides a way to deal with it, one has to see that we are at the mercy of jerks. Play at your own risk and aim the complaints to staff, the people who can actually make a difference.

As he suggested, you can try to arrange such games with people you know instead of random strangers who are likely to be clods.