I guess you're right, I suppose that internally ED has called dibs on a lot of popular stuff, maps especially. That's the reason why we don't have Iraq or Afghanistan for example, they'd sell the best and ED wouldn't want a new third party doing a poor job at it, it's likely the same with certain aircraft. Just speculation of course but it seems logical.
It did surprise me that they let razbam do the Mig-23 though, I recall a while back some ED dev stating that it's something they want to do themselves, so I guess there's still a chance that we see someone else do an early MiG29 or SU25