i guess he means whether it's best to be very cautious and careful, or whether it's better to be cool and relaxed, or whether it's best just to let your killer instinct take over...
personally i think that the purpouse of training in muay thai is to make all the kon muay and techniques instinctual, so that you don't think, you react. If this is the case, your best mindset in the ring is to be completely focussed, without anger, but with plenty of determination.