My wife and I were stalked for a bit by an old high school classmate. We agreed to go out to lunch with him and his wife.
First off, they were not the most interesting people. But the worst of it was that he couldn't say anything without spraying saliva. We were at a diner, so not far away from each other. His first load of spittle landed on my food before I even had two bites.
More distressing was that some had hit my wife's plate and she didn't notice! Crap! I wanted to say something but I didn't have your brother's advice then.
Now that I do, I'd definitely lead with that and follow with telling the fool that he was spitting on our food.
What we did was ghost them. I heard that they think we are "better than them". Umm, yeah, you could say that.