Thors are too slow to do anything against Mutas outside from keeping them out of your mineral lines. Once you move them from your base, Mutas will just go back to owning your mineral lines and production structures. The current maps are way too big given how slow Terran mech is and how weak the air is. Bottom line, Zerg has to make mistakes with their Mutas because Terran sure as heck can't chase them down or contain them with anything.
People saying Thors are the answer have never tried using Thors very much. They're too slow and in low numbers they just get magic boxed, which means you can't reinforce with them either.
People saying Thors are the answer have never tried using Thors very much. They're too slow and in low numbers they just get magic boxed, which means you can't reinforce with them either.