My DS2 hardly ate Dinner for 2 or 3 years from about 2yo to 5yo,
I was always of the school of thought "it is my job to provide healthy & varied food for my children, it was their job to choose if they wanted to eat it"
At age 2 not having dinner won't be the cause of night waking & it's more important to look at the food across 24 hours (or even a week) rather than per meal time. In terms of what you "should" do, it's really more about the boundaries you choose to uphold, it is more likely that if you keep offering fruit & yogurt that he will keep choosing just to eat them, but there is a thread on Ellen Slatter (?sp) & model of eating for the selective child, which is kind of what I did with my children - offer at least one thing you know they will eat (at the same time as everything) & then the food you'd like them to learn to eat & essentially what is on offer is what is the meal, so if it isn't on the table at the start of the meal it doesn't go on later, what they choose to eat is up to them.