It seems that when she first spoke with Keanu Reeves about his ideas, Keanu’s first thought was that Ted should wear a kilt, though by the next time they spoke, Reeves and reconsidered into something a little more traditional.
I had the opportunity to talk with Bill and Ted Face the Music costume designer Jennifer Starzyk, and she told me that, since nobody understood Bill and Ted like Alex Winter and Keanu Reeves, she very much wanted their input for how their grown-up characters would dress.