If it is just sensory seeking RE the food with the finger you could try to give him lots of other chances to have sensory play during the day (sand playdough ect) but if he has some motor skill issues it may be that the spoon and fork because really hard and frustrating (especially if he's really hungry!) We got some zoo sticks to help with finger strength and practice picking up food and getting it to her mouth for my DD that seemed to help. There's still a few things she eats with her fingers that are not really meant to be though, somehow she cannot resist rolling mashed potatoes into little balls before she puts it in her mouth. It drives us crazy but we try to just ignore it.

Can your 10 year old participate in making the lunch, like if he says PBJ can he get out the PB and spread it on the bread or find the pack of hots dogs and whatever condiments he likes to kind of keep his focus on what he choice was?