Officers committing such offences should be tried by Civil Court which would permit a custodial sentence.
A Courts Martial
can sentence an officer to a custodial sentence. However, an officer cannot (
AFAIK) be a guest at MCTC but must serve their time in a civilian prison.
Furthermore, had he been tried in a civilian court, and given he was "only" convicted of possession, his previous good character may have meant he would not have been given a custodial sentence but more likely a fine (click
here).