If you are worried about scuffing, you can always get a mat to put under your chair at the office supply. We have them in our office and it keeps the carpet from wearing and makes the chairs roll really easily.

We did this in El Cajon CA and the city inspector came by and made us tear it out. I think we had a grumpy neighbour who called the city building people. Some towns might allow it but ours did not.

I think I would disconnect the garage doors so they don't open and install a wall in far enough so you can store stuff that doesn't need heat and then you would also have the design wall. If the garage doors don't open he can't see the wall. What a nosey busybody. What difference did it make to him if you used your garage as a sewing room instead of a garage?