Even though you are buffering a point, the resultant buffer is a polygon. You will have a large number of coordinates from that process, so no matter what you are buffering, you'll have to set up the proxy.
urlUtils.addProxyRule({ urlPrefix: "route.arcgis.com", proxyUrl: "http://[yourmachine]/proxy/proxy.ashx" });
esriConfig.defaults.io.proxyUrl = "/proxy";