severe egg allergy?

I have a friend whos son has a 4++ with egg allergies. He had scrammbled eggs, french toast, muffins etc. before they found out. He recently snuck into the kitchen, got an egg and broke it all over himself at his grandms house. He had no reaction. How can he be a 4++? He is also allergic to peanuts. I just dont understand. Hes had so many run-ins with no response. She also asked if he could have honey nut cheerios (which have almonds i think) and they told her to stay away from tree nuts. The first time she called, they told her they were 2 completely different things. I dont have any answers for her. Please help me, so I can help her. Thankyou!