I think he did this cause he only chose the smartest of them. And he put all of them ‘on hold’ with the special diet and all, and in the end Daniel ‘got in’ with the food the Lord approved of! Read it at related link below and especially verse 4: ‘youths without blemish, of good appearance and skillful in all wisdom, endowed with knowledge, understanding learning, and competent to stand in the king’s palace, and to teach them the literature and language of the Chaldeans. ‘. He needed the best advisors in his kingdom, I presume.