In no way is Gramma being rude to Nelson. On the contrary, she is teaching him not to interrupt other people while they are talking. This is common courtesy. Children who don’t learn that it’s rude (and really irritating to others) to interrupt other people don’t magically learn it as adults either. I know this because I happen to work with such an individual. Any conversation when she is in her Eager Mode, you’re lucky if you can get a full sentence in here and there.