Xrefactory violates Emacs license?

[Jeremy Maitin-Shepard]

Hello,

I just became aware of this product:
http://www.xref-tech.com/xrefactory/main.html

It seems to consist of some external process written in C that
communicates over a file descriptor with a user interface written in
Emacs Lisp.  The Emacs Lisp user interface is not merely some additional
interface to an existing program; rather, it is the only interface to
the program, and the program was designed specifically for this Emacs
interface.

The product is sold under a proprietary license and the (non-elisp)
source code is not provided.  I apologize if the FSF is already aware of
this product.  If not, I figured I'd send a message to the list, since
it seems that this product may potentially constitute a license
violation.

-- 
Jeremy Maitin-Shepard