Where I'm from, I've only seen pasta salad served as a side dish. Same for restaurants--I've never seen a pasta salad on the menu as anything but a side. So that's why I thought it was off to see it as a main dish.
Most pasta salads I've had have an oil and vinegar dressing and have pasta (carb) with chunks of cheese and other add-ins. Serving more carbs (bread) and cheese wouldn't have been the obvious addition to the meal in my book. I would have maybe paired a fruit salad and a hearty soup. That said, I would gladly bring whatever the host asked and not tell them my opinion!