My position is (from the FS-X EULA.rtf:
5. SCOPE OF LICENSE. The software is licensed, not sold. This agreement only gives you some rights to use the software. Microsoft reserves all other rights. Unless applicable law gives you more rights despite this limitation, you may use the software only as expressly permitted in this agreement. In doing so, you must comply with any technical limitations in the software that only allow you to use it in certain ways. For more information, see
www.microsoft.com/licensing/userights. You may not
work around any technical limitations in the software;
reverse engineer, decompile or disassemble the software, except and only to the extent that applicable law expressly permits, despite this limitation;The EULA does not make any distinction between the game program itself and the compiled models which, by *my* inference, are part of the "software".
Has it been done? Probably. I suspect that many of the CFS2 "updates" of the stock models have been re-engineered one way or another. Yes, I've seen releases into FS9 libraries of "the stock CFS2 model for FS9", not merely a repaint, but the complete model file as well.
Also, If I create a model and find that someone has decompiled and modified it *without my permission* I will be highly "displeassed", and would reserve the right to take such action, as legally allowed, to safeguard my intellectual property rights.