It is easy to be wise after the event in cases like this. However, I find it strange that the controller was not a little more positive as 2 nm head on is not anywhere near time to be relaxed about avoidance. The inference I take from the account is that the Cessna was a pop up and 500ft below, the next update showed it 300 ft and still going up. The easiest and fastest avoidance with an F-16 would have been
"climb immediately to 2500ft for separation from traffic 12 O'clock 2 miles reciprocal climbing"
of course given no traffic above. At 2 miles or less separation track jitter and tracking delays and slow pilot response mean that a turn could well be onto a collision course.