What changes would make “Bridge Creek Fresh Ginger Muffins” into cupcakes?

Because I’m pretty sure we’re already there.

If not explicitly, the recipe at least skirts a blurry line. Creaming butter and sugar, as well as including two eggs for two cups of flour certainly puts us in cake territory with a dense sponge crumb. But it also comes pretty close to Ruhlman's 2:2:1:1 (Flour, Liquid, Egg ,Fat) ratio.
So where would a “Bridge Creek Fresh Ginger Cupcake” diverge from the existing recipe in your book? What line once crossed makes a batter irrevocably cake for you?

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