I'm not going to tell people who flirt with me I have a son
Why wouldn't you tell them you have a son?
I'm worried if my son gets approached by a strange man.
If you genuinely think the men you speak with might approach your son, then it is good of you to keep his existence on the down low.  It's good that you're looking out for your son's welfare.
Thanks. I only want the best for him.
I think any good parent wants to protect their kids. What kind of people are you interested in dating that might want to hurt your kids? I can't wrap my mind around that fact.