Expectant cootling

Aw! There is now another brood of cootlings on Mount Pond, Clapham Common. I haven't been for a while so I don't know quite how young they are; they don't look brand new, but they're still pretty little...
When the parents find food, the cootlings tip their heads to the side (a sort of receptive gesture?) and then tip their heads up in expectation: it is terribly coot cute, and seems to signal to the parents that they indeed want the food. The cootlings don't always do it, and the parents seem always to head towards the cootling doing it most obviously, so I reckon it must be a form of begging.
It is also quite sweet when a cootling thinks the parent has found food when it hasn't, because the cootling then tips its head and rushes towards the parent, only to slow right up and resume normal posture when they realise the parent has nothing for them. In my eyes they look disappointed, but that is probably my own projection.

I then went to visit the goslings on Eagle Pond which was less fun: they seemed well and even had a spell of flappy-dancing which was amazing, but soon after I arrived, a large youth (perhaps 16 - 18 years old?) started thrashing at animals with a long stick. I saw him swipe at mallards over the other side of the pond, and then he decided that the Egyptian geese were his next target. He came over and started to chase 3 of the goslings that were separated from the others, and whipped at them with his stick. He hit one a glancing blow, but it thankfully seemed unhurt and the three escaped into the pond. I was crouching by the others and as he approached I rushed them into the water too. I felt guilty, but thought it better than letting him catch them unawares.
Him: "You like that do you?" (gesturing with his stick)
Me: "No, no; not really"
Him: "Why not?!"
Me: "It seems unnecessary and cruel"
Him: "I could do you instead; would that be better?"
Me: "No; not really..."
He then started thrashing the irises over my head, before eventually skulking off to rejoin his friends.

I was appalled, and felt very threatened; how could someone attack such inoffensive and, frankly, defenceless animals? I hope the one he hit is OK.
Part of me thought that, for all its awfulness, at least it might make them more wary of humans.