You can wear whatever you want! If you want bike-specific comfort, wear cycling shorts under your regular clothes. Bike commuters wear a whole range of clothes, not just cycling gear. We also ride a whole range of bikes.

And not everyone here rides super expensive bikes. Some of us do, some of us don't, and a whole lot of us have more than one bike--I had a beautiful 1950s JC Higgins 3-speed that I was planning to restore. Man, I miss that bike!

Your bike sounds lovely. The roomies obviously don't know much about bikes (new poseurs, perhaps?), or they would appreciate your classic one!