I just assumed it was because the first google results is "Battlefield Heroes TM on Facebook".
Anyways, in the new game "Star Wars: Battlefront", there are heroes.. So if there's no trademarks on either (I searched uspto and can't see anything), then it's a pretty good name because of the new Star Wars game.
Or someone might want a website about actual war heroes. I don't know what value I'd put on it however.