No one actually used the proper term for these people: illegal aliens.
when did we get laws against aliens? Discrimination!
do you think every time some punk in WoW calls me a "faggot", I should be able to turn around and sue him?
IANAL, but yes, if you choose to do so. But if he says "I think you are a faggot" then you probably won't get anywhere. If he says that he knows for a fact you are a faggot, and assuming that being known as a "faggot" is a bad thing for you, and assuming a ton of other conditions apply, then maybe you could sue him and get some relief.
But, as with many legal options, practical financial considerations often drive the outcome, rather than strict rule of law. What would be your financial motivation to sue the person ("punk" is kind of libelous, don't you think?) that is calling you a "faggot" online? If I were his attorney I'd try to convince the jury that you are not really legally damaged in any financial way by this comment, and that you are trying to abuse the court system by suing over something that would be considered trivial to most people.
None of this means you can't sue - it just means that it probably wouldn't be such a good idea.
In this case, I'd guess the burden of proving actual damage would fall on the plaintiffs. This might be one of those court cases that will get settled for pennies on the dollar, or outright dismissed, and THAT story most likely won't make the wire service, because it doesn't really spark any debate like this one does...