The antonyms for the phrase "more guarding" can be open, careless, or neglectful. When someone is open, they are not guarded or protective, but rather approachable and friendly. Careless means not paying attention or showing little concern for something, which is directly opposite to being cautious and guarded. Neglectful is another antonym for "more guarding," which means not giving proper attention or care to something or someone. Thus, the antonyms of "more guarding" are words that imply a lack of vigilance, attention, or care, which is in contrast to the attitude of guarding.