“I wonder why.”
Probably because being in the minority, she has no real power, but she does have the ability to assert privileges like that, which accomplish nothing, but that the rest of the court is forced to allow her. It’s a petty move, that’s all.
Let her assume the old mantle of “The Great Dissenter” and see what kind of a reputation she can construct for herself while having no responsibility for fashioning workable tests for constitutionality, or reasonable schemes for balancing conflicting rights and interests (i.e., the burden of the majority and especially the justice authoring the majority opinion).