there's been an issue with the way key servers work discovered just a few months ago, a DoS style problem.
It shouldn't stop you from just downloading goatpig's (or anyone's) key, but it's possible that ubuntu have decided to change the way their keyserver works, and you're trying during some downtime or an issue they can't fix, etc etc. Some people shut their keyserver and are exclusively using openpgp.org as a keyserver, possibly some people kept their keyservers up, don't know exactly how the dust settled tbh
go to
https://github.com/goatpig, have a little look through the folders and you'll find goatpig's key somewhere there (I just don't remember where exactly it is, probably in the Armory repo though). This is no more and no less secure a way of obtaining goatpig's key than using a keyserver.
