Yes, it's a "lorebreak", clearly, we have all read the books and know the deal here, we shouldn't be at the Hornburg.

However, had my character (yes my character I've been playing for years, not some session play thing. Did I mention she's a Runekeeper?) not been able to partake in the Battle of the Hornburg I would have been far more disappointed than I ever will be by this "lorebreak". I also expect to be at the Battle of Pelennor Fields, with Faramir's company when he encounters Frodo and at the Black Gate with Aragorn, no matter how unlikely that journey sounds.

This would be a very dull game had my characters stuck religiously to the "lore".