I once saw a little 3 or 4 year old boy lost at Costco as well, wandering around and screaming for his mommy. I was also torn about what to do - I was supporting a couple of adults w. disabilities at the time and having three big and strange(r than ‘normal’) men come up was not the right answer.
But I wasn’t about to walk away and leave the poor little guy to his fate either. So we hung back about 20 feet and kept an eye on him without approaching. Before long a young couple spotted him and took him aside. They were extremely careful about not taking him ‘away’, just to the side of the aisle while they tried to get the attention of an employee. Just as the employee came over the kid perked up, yelled ‘Mommy’ and ran into his (very panicked looking) mom’s arms.
It is a goddamn tragedy that our natural instinct - to help a scared child - has to be moderated by a need to avoid stepping into a false accusation of being a predator. I get it - I have two young kids as well - but I think we also lose something. I don’t know how to balance it though.