@WindSheer - dunno about that, I was half way up a mountain last weekend. But the day job is writing software and as a result I have ended up learning about copyright and software licensing.
Regarding the licence in question, there's a hilarious refusal to clarify here:
A clarification from the prepar3d team.
which you *might* wish to interpret as "just buy it and use it, stop pestering us". As one person on that forum puts it:
''The team has done everything but hit enthusiasts over the head with a hammer with regard to product availability and use without saying things they cannot say. The wise enthusiast would realize that and drop the subject entirely so that the "powers that be" are not annoyed and forced to take action.''
Another poster has also (almost certainly) correctly identified the reason for the clause - that when LM purchased the code from Microsoft it was part of the terms. And the reason for that is of course that MS didn't want LM's product competing with their own "consumer" flight sim(s).