The license for that external file states:

/* This program is free software. You can redistribute it and/or modify */
/* it under the terms of the GNU General Public License as published by */
/* the Free Software Foundation; either version 2 of the License. */

which is somewhat ambiguous.

I checked with the author (Anderson Torsten /Teknous <torsten.anderson@skeria.skelleftea.se>) and he said:

"You can change this to whatever bests fits the way you want to distribute
Moodle to be available to academic institutions!"

So I'll update the file to this:

/* This program is free software. You can redistribute it and/or modify */
/* it under the terms of the GNU General Public License as published by */
/* the Free Software Foundation; either version 2 of the License or any */
/* later version. */

That way, it's GPLv2+ just like the rest of Moodle.