It's not a statute, it's U.S. constitutional case law re: waiving the right to remain silent.
Is there a statute governing a defendant not benefiting from a situation they created? IOW, exercising her right to remain silent but then motioning the court to dismiss (in this case the intent to seek DP) due to the defendant's inability to give a proper plea for her life. Or does the constitution cover that as well?
Either way, JSS could cite it in her reason to deny the motion to dismiss. And then instruct the DT to call their next witness, or JM to cross-examine the secret witness.
I guess what I am trying to get at here is there is no real need for oral argument on this that I can see. Nurmi can argue til he's blue in the face, it won't change the constitution. JSS could rule on this without further arument, IMO, and cite laws that govern situations like this--it wouldn't matter if it was statute or constitution that she cited.
Still, something tells me she will do this in a more round-about fashion, as if everyone involved including the jurors have unlimited days, weeks (months?) to devote to Ms. Arias' right to mitigate her aggravators.