Depends on what you are bringing in. I am surprised that the juice boxes made it passed security. If they had a straw on it.
The reason they try and restrict food and drink items is for the health and safety of the animals.(Its also the reason that you wont find drink lids for the paper cups) I was stopped one day for carrying a McDs cup with a straw in it. Slipped my mind that I was still carrying it. SW has just recently gone back to the paper straws again.
They just dont want the animals to accidentally ingest something and make them sick. (rumor has it one of the baby killer whales about 15 years ago or so, died from an infection it got from a baby wipe stuck around one of its its teeth.) Ive seen the trainers minutes before shows, after a rainstorm get in the pools and pull all of the floating debris out of the pool. One or 2 would stay on stage and spot, while several would get in and collect.