OK. I can only speak from personal experience. The lollipop man, 'Mr. C' who safely guides GDS x 2 and their friends across the road, goes into the middle of the road, stops the traffic and then signals the children to cross, most of whom he knows by name. The children are all very fond of him, he is part of the community and there is always some cheery banter as they cross whilst all traffic is stationary.
My point is, once he ensures the traffic has been stopped, where is the risk in engaging with the children in a friendly manner?