A great response, and wholly appropriate. If success rides on having an interface that no one has ripped off then your startup is going to be very fragile and quite likely to fail, because like it or not, as soon as you get any noticeable traction people will copy what you're doing. That doesn't make copying OK but it's a reality that startup founders face. Startups work when the founders and employees build innovative solutions to problems, and react to customer feedback to make the solution better and better. Anyone copying you is only ever going to be in second place in that regard, so you have an inherent advantage over them. Make the most of it.