Thor: yeah, and we all know how well that went for SCO.
It took 6 or 7 years for the boulder rolling downhill to come to a stop, during which time the status and future prospects of Linux as it existed prior to the case going to court was in doubt.
This may look tangential, but there was a case related to this in the early 1990'ies and it concerned BSD Unix. If I remember correctly, AT&T brought claims against the University of California because BSD Unix was likely to use trademarks and contain code which AT&T had claim to. Prior to that case finally coming to court, companies such as Sun Microsystems and SGI were using BSD Unix derived operating systems had switched to AT&T Unix because it was doubtful that the legal standing of BSD Unix would be upheld.
Because no Unix-like operating system was legally available for free during that time, Linux development got a boost. By the time BSD Unix was found not to use trademarks and code which AT&T had claim to, Linux had matured quite a bit and was well on its way to where it is today. But companies such as SGI and Sun Microsystems didn't switch back to BSD Unix. BSD Unix in its final form did not become available until 1993. Remember how far Linux had come during that time?
You don't want to get tangled up in a court case like this. While it may eventually result in a decision in which a jury finds that the initial claim did not have merit, years can pass during which there are side-effects you don't want to go through with.
Laws can change, the law can remain unchanged but the interpretation of it can change, the law can remain unchanged but its effects may be changed by multilateral international agreements. Here in Europe we shouldn't take the current application of laws concerning patentability of software, and how intellectual property rights are applied for granted. These may change, and it may be wise to avoid weakening projects such as AROS by accident. It did happen to BSD Unix, and it did happen to Linux, in spite of the fact that both cases ended in favour of each respective operating system.