My neighbor's trash can comment got under my skin

Last week I was hauling my little 5 gallon bucket of food scraps down to the community bin in my building's garage. This guy I barely know from the third floor was out there with his trash and goes "you know that just rots in a landfill anyway, right?" I told him no, it goes to a local pickup service that turns it into soil. He shrugged and walked off. But it hit me later that night, he thinks composting is pointless unless you do it yourself in a backyard. I'm in a studio in Chicago, I got no yard, but my scraps still became dirt for a community garden two blocks away. We don't need to be purists about it. Is anyone else dealing with people acting like apartment composting is fake composting? How do you answer that without sounding preachy?