Pinning a pistol mag is not the same as pinning a rifle mag and then calling it a pistol mag.
Not marketed, designed for. If it is designed and intended for a pistol and a rifle (centerfire) it is limited to five. Designed and intended for just a pistol, ten. Designed for a rimfire rifle, unlimited. Designed for a rimfire rifle and pistol, ten.
You can't take a pmag, mark it as a pistol mag and pin it to ten. It was made initially as a rifle mag, and that is what it will always be, so 5 is the limit.
Don't try to rationalize the laws. You'll just give yourself a headache.