Im the orc player. Its my turn and i get to the capital phase. my opponent has two bloodsworn in his battlefield. I play two Rock lobbers, and declare that im going to sacrifice them, to force him to sacrifice his two bloodsworn. He wants to play Brutal Offering in response, saying that According to official rulings or something on the forum, that he can play tactics in response. We look at Action in the FAQ and it says that Actions can be played in response only on the owners capital phase. Is he able to respond to my rock lobbers ability by killing a unit in my battlefield before they were force sacrificed.

He can (assuming Brutal Offering has no restriction on when it can be used). I think you're misreading the FAQ part (assuming you're referring to page 6).

"Action

Playing a unit, support, development,
or quest card from hand are actions
with restrictions built into them. The
restrictions are:

They cannot be played in response to
anything

They must be played during the owner’s
Capital Phase"

The two restrictions are about playing unit, support, developments or quests from hand. Playing one counts as an Action (can be responded to), but have a specific time frame when to use them. Tactics can be played in response to Actions (including playing one of those four types of cards from hand).