Technically, yes. However, I've never seen a tomato in a fruit salad, and no other fruit is used so widely as a base for a sauce for savoury food. Technically a fruit, practically a vegetable
It's about getting the balance of pineapple right and what other toppings there are. Too much pineapple is horrendous, so a nay. IMO, there should be a bit of pineapple so that you get some sweetness and a very slight sourness that complements and highlights the other toppings. A well constructed Hawaiian is a definite yay.
Ewww, what a waste of money and even more money for going for a stuff crust one, tell them to stop being stupid and get a proper one, meat feast, meateor, etc much better