I wouldn't touch some random strangers kid unless the kid needed some help or something.
I'd be suspicious of anyone who would just because the current social norms around it are pretty clear and doing so, to me, would indicate a lack of control.
On the other hand, said social norms have gotten pretty fucked up, in that being charmed by children is a perfectly normal human reaction. I love horsing around with my nieces and nephews. It's awesome.
Seems society has gotten increasingly paranoid when it comes to kids. No wonder so many young adults cant cope with life.