I usually chat with any parents whose children DS enjoys, and just give out my business cards, which I always have on hand, and ask for people's contact information point blank if there's a good match, in that order. If someone is put off by me and my son, who are outwardly normal, nice, clean-cut people showing interest in a friendship then, IMO, it's a red flag about
them. Life is too short to miss opportunities for friendships because of social awkwardness. I've made some of my best friends in adulthood by striking up conversation spontaneously. Why should it be different for children?
I was pleased to hear DS say in response to another parent's comment at the park about "stranger danger" that, in most cases, a stranger is just a friend you haven't met yet. We've become a society so paranoid about remote dangers that we lose sight of living in low-risk situations, so I was pleased to see DS exhibiting a balanced view of personal safety.
I say go for it, within your DS' earshot. Even if the other parent is disinterested, at least your DS will know you went to bat for him.
