I'm not saying he'd use it on him, I'm saying he would destroy the sword. Goku tries to view most fights in a fair sort, as someone who knows nothing of crota but he sees his current foe has a massive sword, for his own safety he will probably try to disarm crota and destroy the sword to bring the battle field to nothing but energy blasts and a fist fight. He's going to try to remove his weapons. And the best removal of an enemies weapon aside from taking it, is breaking/destroying it.