I'm working on a social networking site with a unique name that I own the .com for. The guy who owns the .net is using it for a Chrome extension of the same name. It's not any good and his site has only had like 35,000 visitors over the years. The name is not trademarked and there's no actual registered company under the name. So this probably isn't something I should worry about, but just in case, how do I properly handle this so that he can't claim afterwards that I stole his name (which to be perfectly honest I saw many months after I had the idea).