I am sure somebody did. Dan Brown comes to mind as well. The point is, when the disciple who most likely was not at the Last Supper, Cleophas, recognized Jesus in the breaking of the bread despite having talked to Him at some length prior and not recognizing Him, the first thing comes to mind is the Eucharist, and not historical speculations.
Why would “Eucharist” come to mind if he had never participated in it? The Gospel does say he was a disciple so he would have participated in the “brotherhood” rite. By the way, Otto was a respected theologian and biblical scholar in Germany. His book “The Idea of the Holy” is a classic.