"Why is this even in the Trisquel repos at all?"
Because it's in Ubuntu's. http://packages.ubuntu.com/search?keywords=Miro&searchon=names&suite=all§ion=all But if you notice it's not in later versions so won't be in Trisquel 8.Trisquel used to follow each Ubuntu release that came out every 6 months, and so had more recent versions, but this proved to not be sustainable due to a lack of people power. Are you offering to help out and accomplish this?