Yes it is avialable to anyone, and I don't mind how you roleplay it, provided that you don't fly around omicron alpha going "beep ba beep ba beep ba".
If you're going to roleplay a nomad then try to do some research and slot into the story and information that has already been layed out. There is lots of very specific stuff about how Nomads behave that has been established in this game by Yuri (treewyrm) and others.
Personally I don't see how those 'ships' could be modified for human use, as Nomad ships arn't ships as such, but are infact actualy nomads themselves. I don't see how you could convert a sentient being into a spaceship pilotable by a human, doesn't do it for me.