Actually, as far as Os 4 is concerned, the situation is quite clear to me. Hyperion paid for it, and had the rights to run a Os 4 development on top of Os 3.1, so it's their source and their product. So no doubts about it. And "held hostage" is not quite the right term - they own it, they sell it. Buy it - or don't.
In the same sense, Windows is "held hostage" by Microsoft. But that's only fair. They produced it, they own it, and they can do with it whatever they like. If you don't need this product, don't get it. Unfortunately, the latter part is much harder to avoid than Os 4.
For Os 3.1, however, the situation is not so obvious. I've seen what Cloanto actually bought from the bankrupt estate of CBM (yes, really), and that are the ROM images (amongst others), but not the sources. So that doesn't give them rights on the source code, IMHO, despite Cloanto claiming the contrary. I don't thrust them either. All they have are just the compiled binary images, as distributed on ROM. As soon as they would stick to selling exactly that, it would be ok, but they don't.
I haven't seen anything like that for Hyperion, i.e. I do not know what exactly they got. The license to base 4.x development on 3.1 does IMHO not cover enough rights on 3.1 as such. So maybe the compromise settlement after the process with Amiga Inc. does give them that, but to be sure, I would need to read it, which I have not.
Hyperion nor Cloanto own the source code for 3.1. Amiga, Inc. owns the source code. Hyperion owns the source code to Amiga OS4 and has a license, not ownership, to use 3.1.
Hyperion Entertainment holds an exclusive, world-wide, perpetual source-code license to the intellectual property of AmigaOS 3.1 and additional content as documented in the publicly available settlement agreement between Hyperion Entertainment and Amiga, Inc. which has taken the form of a stipulated judgement.~
http://hyperion-entertainment.biz/index.php/news/38-corporate/167-amigaos-31-source-code-leak-official-statementCloanto owns trademarks to AmigaForever and Workbench. They also only have a license, not ownership, to use 3.1 source code and Amiga trademarks in their AmigaForever package.
In conclusion, Amiga, Inc. is the one pulling the strings. They're never going to open-source 3.1, as they can still profit off of it through Hyperion and Cloanto. Trademarks and licenses are all Amiga, Inc has to profit off of as Bill McEwen couldn't invent his way out of a paper bag quite possibly due to being mildly retarded. His whole AmigaDE vision before the dotcom bubble crash was pretty hilarious. It would be nice to see Bill McEwen try to claim damages from something he himself declared dead. However, just because something seems morally right, doesn't make it legally right.