I wanted to try another distro but Ubuntu won't let you create a USB installer unless is for an Ubuntu image, and the unetbootin did not run either, it would seem they are blocking the options for leaving
you are mistaken Ubuntu: does not prevent you from doing this . there's something wrong with your system that is specific to you. I've use multiple versions of a ubuntu write hundreds of different operating systems to USB sticks. Also, if you had a problem, why post to Hacker News without any repro information at all?