"As for the licence, the modified MPL was chosen so that comercial projects like MOS could use the source code without having to publish their private code. Which is a good thing as it allowed the MOS guys to use and fix te AROS code without giving away their, trade secrets."
Yeah, that sounds very open source to me.
You can still make money with a GPL license. And it would really look more professional and legitimate to allow an object third party to say what the conditions are.
Selling:
http://www.gnu.org/philosophy/selling.html
The world doesn't revolve around RMS or his licence you know.
In the real world the right tool for the right job is how things work. Same thing goes for licences too.