No, this decision does not invent new law (though courts do in fact make law, and it is seen as appropriate for them to do so, both under common law and since Marbury, so inventing new law, had they done so, wouldn't necessarily be innovating). The decision specifically cites the parts of Wisconsin code that apply to rulemaking and why Emergency Order 28 is a rule and not an order. Simply quoting from one part of the Wisconsin code ignoring the other parts that apparently apply (certainly, according to the Wisc. S.C.), is not enough to win an argument.