IIRC back in the COSA days there was talk of use of Trademarks within the code being a potential hurdle to open source AmigaOS. In particular things like the use of "Workbench screen" and "intuition". That was one possible way that AROS could fall foul of Amiga Inc's lawyers.
However I did a quick check a few weeks back, and all of the trademarks that could potentially cause problems lapsed a long time ago, in many cases pre-Gateway. So that should no longer be a threat.