But "Arc" as a name is widely known and used, at least among the HN sort of community, and although it's a niche language it's actively used within that niche. I think you're overstating things; the name "Arc" was not ready for garbage collection.
Taking a look at it from a different angle, even in the case of the legal framework for names - trademark - having Arc the language and Arc the VM thing would be fine.
The truth is, if you don't want people to collide with your name, picking a 3 letter common word probably isn't the way to do it.
Names are hard. :/
I just found out about this language thanks to the link.
More importantly, according to the TIOBE index, Arc programming language apparently isn't one of the 50 most popular languages.
http://www.tiobe.com/index.php/content/paperinfo/tpci/index....