There is Nothing wrong with legal B54-6 (except for the fact that Platinum Trash Byte support still hasn't been incorporated).
Have you paid any attention to all the other Mystery Gift event pokemon obtained from Wonder Cards? If you have, then you will see that all 4th Gen Event Pokemon (whether obtained on D/P/Pt) will all have their Hometown as DIAMOND. This has nothing to do with the WC Distribution exclusivity to platinum.
So to answer your question ("Was it Nintendos WC or is it Legal?"), unfortunately you are wrong.
If i sound harsh, then it is because i have had a hell of day.
