Not someone who played the game much, but a quick glance at the stats suggest that the size of a SACU death ball would be limited by a nuke? I also concede it'd be hard to build a nuke without other players noticing.
The missiles are expensive and take a long time to build (I blieve around 8k vs 3.6k for an anti-nuke), and move across the map so slowly with such a huge warning (pulsating hazmat icon as a radar signature, plus a "strategic launch detected" blaring out the speakers of every player is a bit of a giveaway!) that they can't really hit anything except a stationary target.
Most successful strategies I've seen with them involve rushing T3 and firing a missile from a stationary launcher before the enemy can build antinukes, sabotaging the enemy's antinuke installations with a wave of strategic bombers, or using nuclear subs/Yolona Oss to surprise/overwhelm an enemy with antinukes very late game.
