Was going to suggest something similar: "Of course you may have [yogurt and fruit], just as son as you eat [supper/X amount of supper/X forkfuls of what's on your plate] - it''ll be waiting for you!"
There were times when with my kids I'd alternate, say, a blueberry and a bite of meal food so they were getting some of everything; they ate a fair amount of the meal that way, and as long as they did so, I was OK with it. Had it become an issue of "I won't eat my meal until I've had ALL the dessert," the dessert would have gone away or vastly reduced with the talk about real food being good fuel for bodies to keep us healthy and so on. (Not always without protest or argument, but they got the speech anyway more than once.
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Another suggestion is to speak with him at the beginning of a day, remind him how unpleasant it was the night before with all the fussing about dessert and you're tired of the fussing and crying and screaming, so for a while you're not planning to buy any more dessert food until the issue is settled, or that IF there is dessert, it's going to be something small - for instance a slice of apple or a strawberry or two, and that's IT. But - perhaps he can have some input into his supper as a compromise. (And he may pick a piece of fruit, which is really OK, and which might not end up on his plate until at least some of the main course is eaten up.
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Alternately, you can remind him how unpleasant the night before was, tell him you're not prepared to deal with it again, and that if he throws the same kind of fuss, desserts will be gone for a few days until suppertime and bedtime have settled. How long "a few days" is is really up to you.
Then he gets a chance to adjust his ways, and you can remind him during the day a few times and again at suppertime at the table - and if he throws a fit, so be it.
