You know, I just had a baby, and at the hospital they served me and my husband a special meal. What made it so great was that it was served with a nice tablecloth, pretty folded napkins and beautiful glassware. It could have been any old food, but the presentation was outstanding! In fact, before my husband knew the food was for us, he saw the food outside out room and thought "what ritzy person just had a baby?" then he found out it was ours - he was tickeled! So even if dietary can't help out, maybe you could learn a few napkin folding techniques and catch the tray before it hits the birthday person and I bet other staff would also get involved!
Good luck!