Wait, is this person an adult? The Star Army doesn't hire kids (they hire generally people 20 or older). If this character has less than 20 years of age mentally then he's too young for military service.
It's generally assumed that all Minkan in the Star Army are trans synths who were something else before being Minkan. Since the Minkan body isn't that old there's none of them that have had time to grow up the regular way. The Star Army doesn't generate Minkans the way it makes Nekovalkyrja (who basically get an adult mind planted into their bodies in the manufacturing process).
If he was another species, such as a Nepleslian, when he was born, he would still need to be mentally 20 years old when he was recruited to the Star Army.
I recommend adjustments to the character to reflect the above. The easiest thing would be to make him born as Nepleslian or something similar in, say, YE 18 so he turned 21 in YE 39 and then joined then and finished training in YE 40.