Here's the answer from TK to my question, note how he specificates, mods we can create that change binary files!!!, exes, dll, cat, etc... WE CAN CHANGE WATHEVER WE FEEL NECESSARY. Is simply we cannot share his original files, but we can create a patch that change the needed files, and we can redistribute it, cause as I already said before, the final user will still need the original game/DLC. Is like Blackbird stated, just like Team Daidalos do, and I think is fair game to do it that way.
I don't know If we have the people/knowledge to mod it the sim that way, I hope we do, but first of all we would need to gather a team that is willing to do such mods.
IMHO Avionics are a must, so we can improve the 80's to 2000's planes.