To some extent the question is challenging. It is like "Should a catcher place their fist behind a glove when there is a runner that could steal or protect it behind the thigh?" There are high level outfielders who catch with one hand, there are high level outfielders who catch with two hands and there are high level outfielders who change their approach based on the specific situation. As far as the wisdom of one over the other I can speak to the mechanics and history of baseball.
Back in the day gloves were small and not the cavernous creations of today and so the need for catching the ball with two hands was absolute. ANY outfielder back in the day that did not use two hands was not considered a ball player. Today the gloves are huge and flexible and the leather is supple enough to keep the ball from spinning out of the glove so the ability to catch and secure a ball with todays equipment does not necessarily require two hands.
Then you get to the physics of making a catch and throwing the ball. The transfer between ball and glove needs to be made with as little possibility for error and the least time possible. A fast runner is traveling approximately 25 feet per second and so a .1 second delay in the transfer results in a 2.5 foot advantage to the runner all else considered equal. In reality however all else is not equal, the velocity of the throw, the accuracy of the throw can all be impacted by the body position, momentum toward home, fluidity (integration of the transfer with the throwing motion) of the transfer etc.
IMHO a scout at a showcase watching the outfield is looking more for velocity and accuracy in the throw than anything else (ie. 1 or 2 hands) because those are elements of the game that can be taught and communicated to a player after they are on the team or in the organization. What you cannot teach is Benedetti's 97 MPH strike to home from left. Don't misunderstand, they will look at shear speed they will look at path to the ball on line drives, they will look at stability and comfort in travel to the catch, they will look at the need to drift under the ball versus judging, they will look at reaction time the ability to read the ball but at the end of the day throw a laser and put it in the catchers or third baseman's mitt and you will have accomplished the goal of catching their eye. P.S. if you hit 3 dingers you will also catch their eye...