It is very good to see this, in my view is an integration of the FlightGear with X plane.
And I don't see anything illegal (see in About This File the DISCLAIMERS).
FG has an excellent level of development by developers (logically), it's a volunteer work that dedicate their time to make this simulator better every day.
Look the link:
http://forums.x-plane.org/index.php?/files/file/39005-72-flight-gear-liveries-for-vskylabs-dc-3/&tab=reviews