Open source doesn't necessarily mean non-profit. Consider Red Hat. Making plenty of profits from a completely open OS. If you look at the Open Source model honestly, you will recognize that a company can reap a lot of benefit having so many people working on their program and/or OS for "Free," and they can discover new ways to profit from it. Again, I use Red Hat as an example; there are many others who have benefited from Open Source, including (but not limited to) Sun Microsystems, The Mozilla Foundation, and even Google.
When it comes to Amiga, there are more profits to be made from the brand image than there is from the OS. Making it open source would dramatically improve the brand image of Amiga.