agree, it's a Frank Lloyd Wright thing maybe mixed with Esperanto. It comes from abbreviating United States of North America (USONA), then because it's popularity around the time of it's invention by Zamenhof, was adopted into Esperanto as the name of USA, somewhat modified as "Usono" https://eo.wikipedia.org/wiki/Landnomo_kaj_lo%C4%9Dantoj_pri_Usono

I'm not sure if @[email protected] is an esperantisto or if it's used in other contexts as well