Anything submitted to the Wiki is on the basis that anyone else may edit or fiddle with it. OXPs are submitted under the creative commons licence. The author (stickty speaking) owns the copyright, but licences users to use or distribute the OXP as long as they don't sell or charge for it. In practice virtually all OXP authors don't assert copyright and are pleased and flattered that somebody thinks their stuff is worth writing about or pinching to use in another OXP (its good manors to credit the orginal author in the readme though). I expect the author will be pleased if you want to add some background, but if you are in doubt, send him a PM asking him for permission. At the end of the day, Oolite is a fun project and everbody is doing stuff for it on that basis.
A virtually definitive assessment, this should be a sticky and also included in the WIKI.