Looking at the Javadoc: http://docs.oracle.com/javase/6/docs/api/java/util/Locale.html
and the full locale list:
http://www.loc.gov/standards/iso639-2/php/English_list.php

I don't see UTF-8 listed.

Ideally we'd do a case insensitive comparison, but since we don't control the HBase side of things, that's not feasible.  Locale.ROOT claims to be language neutral(compared to Locale.ENGLISH), but I'd have to write a test to make sure that it behaves as expected.