Cook the rotini according to package directions. Drain in a colander, then run under cold water until pasta is chilled.
While the pasta is cooking, slice the smoked sausage into rounds, then cut each round in half.
Add the smoked sausage, shrimp, celery, bell pepper, corn, and green onion to a large bowl.
In a medium bowl whisk together the mayonnaise, mustard, garlic powder, cajun seasoning, and hot sauce. Taste the mayonnaise mixture and add salt and pepper as desired.
Add the cooked and rinsed pasta to the shrimp mixture and stir.
Pour over the dressing and stir until everything is well coated.
Chill for at least 1 hour before serving.