So if I were to fork IC2, and develop that, would I be allowed to release it? Obviously I would not make any money off of it.
You need Special Permissions from the IC2 Dev team, and you have no permission to make money with it because it is licenced under the same term like IC2 Exp.
Easier answer: As long you got a release permission you are allowed to do the same stuff as IC2 do.
Or did i understand you wrong player?
If you ask Player nicely, I'd imagine he'd be okay with it.