Military use??? You understand what two way transmission means during a conflict? An enemy tunes an antiradiation missile on your frequency, and voila...
China already had military digital satellite coms working by late nineties. For them, it was of even lesser utility.
Perhaps some background info can help. Beidou I was developed in early 2000s. And at that time Chinese military satellite wasn’t advanced at all. Even though beidou I is vulnerable to anti radiation missles, it’s the best they have and at least it worked well for purposes such as border patrol and terrain survey.
My point is that many things in China may be explained by the party wanting more control, but two way transmission of beidou I is not one of them.
China already had military digital satellite coms working by late nineties. For them, it was of even lesser utility.