I outlined the situation to DS8 and asked him what he thought you should say. His suggestion: "She could tell him that she knows someone on the internet whose son [that would be him :-)] is very very good at maths. And it somehow .... got out.... that he was very good at maths, and now older children keep asking him to do maths problems even when he doesn't want to." (This is now at the level of a minor irritation - it's coming from children 4ish years older than him, who are intrigued that he can do more maths than they can, not from his own classmates, who accept him - but clearly he feels he could have played his cards better earlier on, though I don't remember any very blatant incidents!)
DS adds, "Or she could tell him that it might hurt people's feelings. But since he's only 6, he might not really get that, and it might not have much effect."!
