[MrHobo]

If you realize a terran is turtling up and going for a ridiculous build like this, best thing to do is try drop harrassing/pushing consistently while taking expos. That way, his production and economy will (hopefully) be much weaker than he had anticipated and he won't have nearly as much as he wanted (ghosts + nukes = a lot of gas). If you don't kill him with dropping, you'll cripple him enough to overrun him with your own army (ultras + infestors can be the most effective unit composition against this scenario).