If in a lesson, I have a different idea to that of my teacher as to a passage or interpretation, he leaves it to me to decide what I prefer, if either is acceptable and is just a matter of taste. Maybe you should have a talk with your teacher about this and that his ideas are not the holy be all and end all, and that they are flexible to change.
Even as ice cream trucks didnt exist in the days of Schumann, and thus his music could not be connated to it then, I'm very sure he wouldnt of written something with the intention of it sounding juvenile and mechanical. He was a very emotional composer and all his music is gorgeous and soulful, keep it so.
If I were in your position I would talk to my teacher, hope for a change of attitude, and if it did not happen, I would find another accompanist, and play it my way anyway. Because ultimately, you are the soloist and the one in the spotlight and the public will critic your playing, style and interpretation and general performance, not your teacher's. Dont allow your playing (and most importantly, your performance) to moulded into that of your teachers, especially if you dont agree. It is not good for your musicality, individuality and career. What makes a great pianist, IMO, is individual style and character. Its one of the mst important aspects of piano playing.