I didn't say starve a bird! I did a 180 on the diet of my sun conure. She snubbed pellets for nearly 2 days before she gave into eating them so I can say as fact that birds will not "starve to death for sure" if you give them "food they aren't familiar with".
That's not to say every captive bird on earth will eat their new food as quickly as mine did tho. If the bird in question doesn't eat their new food within a day or two, try something else and go with a mixture of the birds "familiar" food. Yes, a bird has to eat something, preferably a much varied diet!