One way of looking at this is by first looking at two words:
Worry by its very nature, implies fear, anxiety, uneasiness and apprehension.
A Simpleton is simple in a 'not too intelligent sense' or being low in common sense and not very smart.
Genius implies scholarliness, talent, academia, potential and wisdom.
This is a difficult one. A worried genius can also mean a 'concerned genius' like Einstein, and on the whole he is said to have been spiritually advanced. Again, not only Ramakrishna, but quite a few Seers, had very little schooling. They were so full of joy that Kings and Queens used to go to them for advice. Some did not teach, but simply roamed the world in a seemingly mad drunken state. Yet they were far from stupid.
A combination of Joy and Genius, would make more sense, but since we are meant to come up with an answer, I will say that both have their merits. The Sage shares the joy and simplicity of the Simpleton, and the genius who shows wisdom and potential, is truly awesome! Both compliment each other. I have just noticed, that Bronwyn demonstrates this quite well in her answer. Hari Om!