I am at least. It's "a reasonable approach to take" in that it may be an effective mechanism for accomplishing certain goals like diluting the power currently concentrated there or preventing some specific action the court may take with its current majority.

I don't think there's a framework that can universally tell you whether supreme court expansion is always good in all cases or always bad in all cases. Taking effective action is bad when you do it for bad reasons and good when you do it for good ones. Unsatisfying but there it is.