Because the area surrounding the food site is not open to the public when the site isn’t distributing food. And after soldiers signal that this is a combat zone not open to civilians by firing warning shots, and people keep approaching them anyways, I have no idea how you or the article can determine that the soldiers or aid workers are not under threat in that situation.
The fact that (an anonymous source claims that) some 18 year olds employ some gallows humor when under incredibly damning situations is certainly not unique to Israel. I doubt you can find one army in the world where enlisted troops don’t make those kinds of jokes. It’s hardly evidence of murder.
It’s not something I advocate for; I think they should create more aid distribution sites and expand the program.