I think the issue could be that as it's not an entertainment product there's likely to be more interest from the actual aircraft manufacturers, who wouldn't want inaccurate renditions of their aircraft being used for training or competing with their own or officially licensed products.But how does one argue about distributing freeware one has learned to create? - for others to learn how to fly that particular model I suppose & maybe learn how it was created?
This can also hit payware developers whose licence from the manufacturer may only cover them for entertainment products for the same reasons, e.g. if it's an officially licensed Boeing 747 add-on for a training sim that could open Boeing up for liability further down the line.
Obviously a lot of this is theoretical but ultimately the original manufacturer owns the rights to their design and it's up to them how they choose to police it, with P3D being officially for training and simulation they may be more cautious about things.