M.O.
I think you were right to report it. This guy's conduct will likely chase away other volunteers, which will harm the whole homeless community.
However, I agree with the other volunteer to a slight extent too. You are dealing with a mentally ill population. Some of them will say inappropriate things. So you should report it -- yes -- but I also recommend not taking it too seriously and just taking it in stride. It's highly unlikely this guy will ever seek revenge or anything -- he probably just doesn't have an internal "filter" for inappropriate comments.
I worked with developmentally delayed teenagers for years. The guys had the hormones of any other teenage boy, but they had the reasoning capacity of preschoolers. So, wildly inappropriate comments, every single minute. By my third day on the job, I had completely tuned out the fact that these remarks were directed to me. The important thing is, they came from a harmless person, so that made the words harmless too.
In other words, report, but also relax. And keep volunteering! It's wonderful that you're doing this.