Either that or they won't make the calls. If they were to try insulting the voters or the R candidates, they run the risk of being exposed as people would call news stations and the GOP to complain.
I don't think it matters either way to them. They call in to a radio station and start shouting about anonymous rude GOPers? That might actually fit their intentions MORE.
When I was doing my GOTV calls from home a couple of hours ago, I wondered what kind of controls the GOP has to prevent this kind of thing. I wonder if they have phone numbers to a phone bank manned by people monitoring the GOTV calls sprinkled throughout these lists. I would hope they have some kind of caller ID or some way to trace the calls to track down people who are committing this fraud.