Don't be silly, it was never under "Mounted Weapons" to begin with.
I can see it under "Map Items" and "Tactical", but not "Mounted Weapons". In fact, it doesn't show up in the category page. Nonetheless, I can't really seem to find anything and the wiki activity says that no one has changed its category.
Also, try to be a bit more descriptive when explaining where you saw it. I can only assume that you saw it under "Mounted Weapons".