GPL-script to be run on a non-free interpreter

[Ralf Treinen <treinen@club-internet.fr>]

Is it OK to distribute a script, which is
- licencend under GPL.
- intended to be executed by a non-free interpreter.

Background: I'm intending to package maria (ITP at bug #146320), which
is licenced under GPL. Besides the main tool, called maria, it also
contains a script, called maria-vis, which can be used to visualise the
output of maria. It is a script for the "lefty" interpreter, which is
part of the non-free graphviz package. The first line of maria-vis is

#!/usr/bin/lefty

I was intending to split maria into several binary packages, in particular
- maria: the core. Goes into main, suggests maria-vis
- maria-vis: the mentioned script + manpage. Goes into contrib, depends
  on graphviz.

When I sent my ITP on debian-devel today, Moshe Zadka claimed that
even distributing maria-viz would be illegal.

http://lists.debian.org/debian-devel/2002/debian-devel-200208/msg00188.html

Can please someone advise whether this is really the case?

Thanks. -Ralf.
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