I would expect the Imperial Legion to try to avoid murder, being as it's, you know, illegal and all. And I'd expect the Imperial Legion to want to not give the locals another reason to want them out of Morrowind, it's bad PR.
On the other hand, while it might not be behavior the Imperial Legion would encourage, I actually could imagine some of the more... hot-headed guards picking a fight with someone who angers them, especially if they happen to be drunk at the time. It must be remembered that just because a character is part of a faction doesn't mean that character will automatically exemplify all the ideals of that faction.
Don't attack them unless they attack you. Knights do not taunt officers of the law. A Knight of the Imperial Legion is Lawful Good, and respects other officers of the Law. If you want to become more popular with them, do some quests for the Temple or raise their disposition with bribes, spells or speechcraft like a real virtuous man would.
Bribing or using magic to influence people against their will are really not the first things that come to mind when I think of "virtuous man".
Now ignoring their insults and letting your actions speak for you on the other hand is the most virtuous thing that comes to mind (In other words, raise your reputaion through quests so everyone likes you more.) the problem is that Morrowind doesn't really encourage this, in fact, unless you have a high enough speechcraft skill to rely on admire, bribing or using charm spells if you can are the ONLY ways to complete certain quests, but it's never really necessary to get ordinators to like you.