Spoken like someone without a lot of legal experience in technical fields. 
You might be surprised how often data providers have existing APIs that customers are not allowed to use due to compatibility and contractual reasons, not just one or the other.
The point is, it sounds very much like there’s a combination of issues involved here, both technical AND contractual, if you read all the statements from MS/Asobo, the folks at Working Title, and the various 3rd party aircraft developers together in context with one another.