That could be. But in that event the appropriate approach for the defense woud be to say so in their argument

I disagree.

(That is, I think that elaboration of his parenthetical remark would not be appropriate. He needed to only concern himself with explaining the main part of what he was saying/writing, not every detail. Especially not something written in parentheses.)

The expert's main argument was "commingling", and that was clearly the main thrust of my comment, not the part about the expert's parenthetical about labels.

(This is a perfect demonstration of why the expert should not elaborate their parenthetical remark. Either someone gets it or they don't. And some won't, no matter how much elaboration is provided. Judges come in both flavors; the expert is right to speak to both audiences and choose how much to write for each.)

The main issue remains what does "commingling" mean and imply in this sort of situation that an open minded judge may safely be expected to know, and what is the known actual extent of cross contamination or considered likely extent in this particular case that the judge can be expected to know based on other relevant material and argument already provided?

(This is just an elaboration of what I already wrote in my prior comment. I suspect it won't help -- I suspect you'll still miss the point and fail to address this central part of my comment. Likely you'll focus on some minor detail instead or just not reply. If so you'll be illustrating my point; no amount of rational elaboration helps a closed mind see what is plain to see for those with an open mind.)