Tec, as AH has grown, HTC has evolved their quality control.
Allowances that might have once let a skin into the game may no longer be open. For example, plane versions vs skin versions (skinning a P-38E on a P-38G plane, or putting a 109E-7 onto a 109E-4).
As HTC has increased the quality and fidelity of their flight models and 3D models, they have also changed some of the ways skins can be accepted onto those skins.
Currently, they say "no" to neutral countries, end of story.