Olives are quite nutritious, providing heart-healthy monounsaturated fat (per olive, the fat content is fairly low). Yes, they can be sodium-heavy, but rinsing beforehand can cut down on the sodium substantially. When I was a kid I used to eat whole black olives all the time - I called them "belly buttons." Just like anything, moderation is the key. Any food that's canned, pickled, brined, etc. will have more sodium than fresh foods, so subbing out canned chickpeas is an alternative but won't solve your sodium issue. Hummus is better, or try cut up grapes, grape tomatoes, frozen (thawed) peas and carrots - anything he can finger-grasp but still have a good veggie snack.