Because nobody can make an actual nuke in this game, only some weapon that has a stuff load of emitters jam packed into its explosions.
It's pretty hard to make a nuke in this game because it requires a lot of special scripting to make it actually look like a nuke. For it to actually look like a nuke you need bright light everywhere, a multi-colored mushroom cloud and a shockwave, while also killing anyone within 0.5 miles in-game.
This is why we have no "good proper" nuke. Bushido's Mini-Nuke is in a sense not technically a nuke because it's just a big explosion. No mushroom cloud or anything.