Akbar and a pattern of violence

OK. I realize I'm not the brightest bulb in the box, but, during a sentencing phase, when a pattern of violence is being established, why on earth would a judge do this:

the military judge overseeing the case said he would not allow prosecutors to introduce evidence of a fight Akbar had with a military police officer in the court building last month. Akbar secreted a weapon in an office and stabbed the MP in the neck while in the restroom, but the judge said that "opportunistic stabbing" didn't show a pattern of violence.

Really? I guess my feeble understanding of words like pattern and opportunistic needs updating. I thought pattern was something like, you know, repeating facts and/or actions like, you know, maybe a guy that would hide a knife and then attack someone in a bathroom as well as toss grenades into tents is, you know establishing a pattern. While I'll grant the judge, I'm sure the acquisition of the knife may have been "opportunistic" (we don't have any facts on this, so let's go with it), the fact that the guy hid the knife and then used it later, certainly strikes me as premeditated, not simply, oh look, I've got a knife in my hand maybe I'll use it, what an opportunity.