And the correct answer is…
It is perfectly fine to use your chopsticks to maneuver food to your mouth while sipping.
In fact, this is what you should be doing.
When it comes to delicious soups or broths in Japan, most establishments do not offer spoons. This is especially true for miso soup. Instead, you should pick up your bowl to drink the liquid and use your chopsticks to pick up solid ingredients.
When you eat soup in Japan, hold the bowl in your non-dominant hand, four fingers on the bottom with your thumb on the lip to provide stability. With your dominant hand, use your chopsticks to grab the non-broth components, taking care as they will be more slippery. Occasionally bring the bowl to your mouth and sip your soup.
Enjoy your soup!